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Engine Specific Info and Questions => IDI Engine => Topic started by: BlackTieTD on June 01, 2004, 08:51:40 am
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IDI fuel economy comparison:
BlackTieTD - 1982 2-door Rabbit, ~1800Ibs no driver/fuel, 1990 1.6l TD (MF) on regular pump diesel
mixed city/highway, wearing my heavy right shoe:
5.87L / 100km | 40.73 MPG (US)
Dr. Diesel - 1992 4-door Jetta, 2720Ibs, 1.6l TD (MF), modified injecion pump on ze spezial jet fuel
4500 rpm 130km/h highway cruising, with common jaunts past 6000, (CLOSE RATIO TRANS!!) and a very heavy foot in the city:
11.00L / 100km | 21.73 MPG (US)
TDIMeister - 1997 Passat, 3400+Ibs, 1.9l TDI, modified extensively from stock
Timed at 10.787 on the 1/8 and 17.079 on the 1/4.
Best: 5.00L / 100km | 56.5MPG (Imp.) or 1420 km range per tank
Average: 5.70L / 100km | 49.6 MPG (Imp.) or ~1250 km range per tank
Worst: 6.20L / 100km | 45.6 MPG (Imp.) or ~1150 km range per tank, and that was BEATING ON MY CAR!
fspGTD - 1981 4-door Rabbit GTD Autocrosser, ~1800Ibs, 1.6l GTD (MF), SCCA FSP Class
On cross country road trips:
4.71L / 100km | 50.00+ MPG (US)
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i have a 1982 2-door Rabbit with a 1990 1.6l TD engine, MF code.
i'd like to compare my fuel economy numbers with others with a similar setup.
i estimate a total vehicle weight without fuel/driver at about 1800Ibs.
the fuel tank, i'm not even sure exactly how big it is, but it will take about 44 litres of fuel if its bone dry. 45L tank?
when i first did the engine swap, i got a consistant 630km per tank, and i mean, i'd roll into the gas station on fumes at 630km bang on 3 or 4 times in a row before there would be any fluctuation.
that was low, and that was with a noticable shimmy, especially at 60-70km and 120+km. i changed the rear tires and the shimmy is gone now...
the fuel economy has definitely improved, but i havent run a full tank to bone dry yet... but with the way things are going i will be at minimum 700km per tank. that bad rear rim really effected the economy!! :shock:
right now i'm at 690km and i still have all of the orange 'empty' area left on the fuel gauge. projected fuel economy is about 740-750km/tank.
44L / 750km = 0.05867L / km
so about 5.867L / 100km
to fill from empty, i paid an average of $29 when diesel was 67c/L and now about $32 since its refused to fall from 72c/L.
that works out to:
at 67c/L: 3.867cents / km
at 72c/L: 4.267cents / km
or about $8.50 to drive to toronto and back (200km).
it used to cost me $16 for that trip when i was going to school there and was driving a chevy 4-cylinder, in good tune.. and that was when gas was in the 60s (its rarely below 85cents/L now).
for comparison, my friend's '97 civic is about 9 cents/km and that is known to be a fairly economical car. $18 for the toronto trip at today's pump prices.
how do my numbers compare to yours?
i still have to change wheel bearings, squeeky passenger front brake, shaky passenger balljoint, and get an alignment.
..and i haven't been able to shake the lead foot syndrome yet!
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2720 lb A2 jetta, lotsa 4500 rpm 130km/h highway cruising, with common jaunts past 6000, (BLAST THIS CLOSE RATIO TRANS!!) and a very heavy foot in the city= 500k/tank
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doc: CHANGE YOUR GEARBOX. i assume 55L tank in your smoke-mobile?
i've added your numbers to the top of my original post...
keep the numbers coming folks!
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Very long ratio w/peloquin coming soon to a sooty jetta near me. hehe
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As a point of comparison (just because I like to gloat LOL) :lol:
1997 VW Passat TDI modified extensively from stock
Weighs easily over 3400# wet and with middle-weight driver (me)
Timed at 10.787 on the 1/8 and 17.079 on the 1/4.
Best: 5.0L/100km (56.5 Imp. MPG) or 1420 km range per tank
Average: 5.7L/100 km (49.6 Imp. MPG) or ~1250 km range per tank
Worst: 6.2L /100km (45.6 Imp. MPG) or ~1150 km range per tank, and that was BEATING ON MY CAR! 8)
All figures are over a whole tankful.
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TDIMeister... looks like some good figures but i bet mine is still quickest in the 1/4 :D (dr. diesel you stay out of this)
what size is that tank? 72L?
nice to see that your figures are better than mine with the new technology, but not by much! you of course are hauling around the weight of almost two of my car though :?
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My Rabbit presently gets over 50 mpg on it's cross country road trips! :) It's quite a stark contrast to the gas-V8 powered tow-rigs trailering their race cars that I sometimes road trip with (which I don't think manage much over 10mpg!) It's fun to pay a fraction of what they pay when I need to fuel up, and still only need to fuel up every other time vs them. ;) Although I'd love to have a tow rig, driving the car to the cross-country race events sort of goes hand in hand with having a diesel racer! :)
I'm sure my Rabbit gets a lot less than that during actual autocross driving though. 8) I rarely fill it up all the way when I expect to race with it, so I don't measure mpg when racing. I only can measure it when I fill it up all the way, which is when I am road tripping. :)
I don't drive it around the street in city type driving enough to know what it would get. But back when it was a daily driver, it got 41-42mpg originally, as a normally aspirated diesel, which got upped to about 44 when it got turbo'ed, and progressively upped to about 48mpg after it got big exhausted, intercooled, and long-ratio transmissioned.
All given measurements are in US Gallons.
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FYI, keep in mind when making comparisons:
1 liter = .264 US gallons = .220 imperial gallons.
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good numbers jake.
so if you were to run a complete tank, 45L, completely dry, you'd make it about 955km.
if i were to do the same, i'd make it about 767km.
that gives me a lofty goal to shoot for... i was going to settle for 800 or 850km per tank, but if you can get 950km cross-country, i'll have to shoot for that.
i'll change wheel bearings, front brakes, passenger balljoint, and get an alignment. 2.25" exhaust, intercooler, and just sit and cruise at about 110-120km/h and do you think i can bump the ~760km i'm getting now to ~950km? i think its do-able... i'm usually pretty heavy on the throttle!
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My '81 Rabbit came with the "10 gallon" tank. I almost never fill it up more than 9.6 gallons at once. But I like it, because I can run it as low as I want and it never seems to starve when I'm racing. There is an 11 gallon rated fuel tank for the '84 (maybe '83) Rabbit diesels... sounds like maybe what you've got?
That ultra-low ring and pinion that now is in Mr. Dave's posession was the single modification that made the biggest improvement to my Rabbit's miles per gallon.
I wonder if we tried using tires like the Electric Vehicle guys use, that are really low rolling resistance, what effect that would have?
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Just last week I got 925 km on a tank when hitting the red mark on the gauge, this on my 91TD JET (somewhat modafied but still efficent). Thats half city/highway driving and crusing on highway at 3250 rpm.I also have a fairly heavy foot ,Its tempting to just leave it rarther than dump gobs of fuel in :? It seems that with the more fuel I dump in there Is just not enough air to make it work EFFICENTLY, without polluting excessively. :!:
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My 1984 Jetta Diesel (Normally Asthmatic, 5 speed - 7A transmission) gets about 46mpg in a mix of city and country driving (2 and 4 lane rural highways, a little Interstates highway driving, plus small town driving). On long, cross country trips, it varies depending on which way I'm going (and which way the winds blow). The best I've gotten from a tank was 54mpg (mostly I95 along the Florida and Georgia coast). The worst was I80 westbound across western Nebraska and Wyoming. I had to run 4th gear then against the 30-40mph headwinds, and I only got about 38mpg.
It's about 2,150 pounds with me and another passenger in it (typical for around town driving, 2,025 pounds with just me, close to 3,000 pounds for the cross country trips with 2 people, luggage, clothing and personal gear for both, plus camping gear, cooking gear and other assorted cargo). Mods are cowl induction fresh air intake, K&N filter, Autotech Tri-Y header, Injection pump adjustments (full load fuel increased, timing advanced until it starts getting loud with the cold start knob pulled [about 1.06mm]), stock 1 5/8" exhaust from the header back with stock resonator and muffler (changing that to 1 3/4" aluminum pipe straight to a Supertrapp), BMW 5.5x13" "alpina" style wheels (although I got the same basic results with 5x13" early Scirocco wheels), rear disc brakes (now aluminum calipers), and cheap, light weight 175/70-SR13 tires.
That's on conventional diesel. I'll have it going on the straight veggie oil conversion this week or next, and we'll see how it does on that.
My previous diesel, a 1980 Rabbit diesel, 1.5L, 4 speed (GC transmission) got about 45mpg in city/country driving, about 42mpg on long trips, and one time I ran a Porsche club drivers school in it at Roebling Road (Savannah, GA) and stomped it all the way down to 36mpg on the track. With the GC 4 speed, highway mileage suffered some because it turned a lot of revs at highway speeds (65-70mph). I ran it on 155R13 tires and 175/70R13 tires on the street and 185/60R13 DOT race compound tires the weekend on the track. It got slightly better mileage on the 155R13's than on the 175/70R13's. It handled much better on the 175/70R13's and stuck as good as any ITC rabbit on the 185/60R13 race tires.
For that track weekend, it also had the racing coilovers, springs and shocks installed from the ITC Rabbit I drove at the time. My co-driver rolled the race car and did some severe body damage to it one week beffore the Porsche Club school, so I put the race car suspension on the diesel and ran the school in that. My main purpose at the school was to learn the track (I'd never raced there before that time) and the diesel did provide some interesting feedback about your driving line. If you slip the thing off line, it scrubs off speed that you don't get back for a long time.
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5000 pounds?!
Oh yeah, I forgot about the "lead sled"... :shock: :wink:
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Blades - 1992 Golf, 1.6l NA on decent diesel with wannabe-close ratio transmission (3900rpm @ 120km/h)
5.72L / 100km | Do the maths !
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Blades - 1992 Golf, 1.6l NA on decent diesel with wannabe-close ratio transmission (3900rpm @ 120km/h)
5.72L / 100km | Do the maths !
OK, 5.72l / 100km in mpg (http://www.google.com/search?hl=en&ie=UTF-8&q=5.72l+%2F+100km+in+mpg&btnG=Google+Search) = 41.1214308 miles per gallon.
Or, 5.72l / 100km in feet per fluid ounce (http://www.google.com/search?hl=en&lr=&ie=UTF-8&q=5.72l+%2F+100km+in+feet+per+fluid+ounce&btnG=Search) = 1 696.25902 feet per US fluid ounce.
Or, even 5.72l / 100km in furlongs per teaspoon (http://www.google.com/search?hl=en&lr=&ie=UTF-8&q=5.72l+%2F+100km+in+furlongs+per+teaspoon&btnG=Search) = 0.428348238 furlongs per US teaspoon
I love that google calculator.
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Just got back from a trip to Montreal. Got 825km on 49.3L, or 5.97L/100km . Works out to 47.31mpg (imp) or 39.39mpg (US). This was combined high speed (130km/h) highway and some Montreal city driving (which differs somewhat from "normal" city driving :D ). I was also hauling about 400-500lbs of tools and parts with me...
Car is '97 1.9TD jetta, intercooled, injection pump mods, exhaust and a bit more boost than stock.
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1989 VW Jetta NA Diesel (STOCK!!!!)
487.5 Miles on 8.756 Gallons Just Filled Up at 11:45pm
Calculates to 55.7 MPG (US)
Don't know what that is in L/Km, but I don't really care.
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Hi all the frankenbunny gets a very consistant 47 mpg commuting from sonoma valley to treasure island in the sf bay........ with a fn trany from a picup. on freeway trips it gets over 50..... my ford 1ton van (6.9D) gets 17 on a good day of driving at 55mph ( no overdrive, yet) :shock:
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Hey moosiah!
We're almost neighbors...I live up in Sonoma County near Lake Berryessa, and work at Travis AFB.
BTW, what is the "frankenbunny"? :D
Stan
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some good numbers and interesting cars out there. thanks for the replies. i'll add your info to the top post, add any extra info about your car that you'd like so i can include it all. weight, motor, tank capacity etc etc...
:)
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My Rabbit's 1.6lTD is engine code CY not MF. (Not that I understand there to be one difference compared to a solid lifter MF! ;) ) Oh yeah also although the weight of the car sans-driver, race-ready is 1800 lbs, the weight of the car with race gear loaded in the back plus myself is actually more along the lines of 2100lbs. Some modification details that might be relevant for mpg calculations are: it is lowered some and has a US-style GTI airdam, but has tall and high-treadwear rated 175/80/13 tires ...or was that 185/70/13... 10mm wider same aspect ratio as stock circumference tires I know for sure. I use them for roadtrip driving, 2.5" exhaust with freeflow downpipe, and for gearing, it has a 4K with .71 fifth gear conversion (that has a 3.94 Ring&Pinion.)
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1.9td with "mods" - it's turned longitudinal, has 1 7/8" straight pipe ( 4 90 degreee mandrel bends) pushing a little red brick 65mph@2750 rpm on 35" tall tires, gets 27 mpg. It's workin' hard. I wouldn't mind 30 mpg, we'll see what the intercooler does.
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engine - MF code 1.6TD hydraulic lifter
transmission - 7A code 4+E 3.94 final, .71 fifth gear
mods - exhaust, increased fuel, KKK03 turbo, intercooler
chassis - 84 Scirocco ~2300lbs
fuel tank - stock 53L
Under daily driving (one way commute ~100km) I typically average 5L/100km, or 56.6 mpg Imperial, 47.2 mpg US, with moderate to heavy use of the left foot. Complete disregard for the visbility of motorists behind me results in 5.6 - 5.8 L/100km consumption overall.
The use of stanadyne performance formula usually knocks fuel consumption down noticeably, and I have recorded 4.6L/100km on long freeway hauls of constant 125km/hr speed.
The lower CD of the Mk2 Scirocco (.38 over .42 on the A1 Golf) and the economy gearbox make this combination a very economical commuter.
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nndra ?
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Indeed, it is I... :)
Sorry - couldn't remember what userid I had on the old forum - too much soot in the brain I guess...
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Hey good to hear you're still breathing! Welcome to the new forum!
BTW - type b53 - is that what they called the scirocco? (I'm pretty sure the technical name for the Golf 1 / Rabbit is the "type 17" :D )
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Hey good to hear you're still breathing! Welcome to the new forum!
Thanks Jake. I was searching for something and tripped over it, thought I'd drop in. Looks like a nice new home for the forum.
BTW - type b53 - is that what they called the scirocco? (I'm pretty sure the technical name for the Golf 1 / Rabbit is the "type 17" :D )
Type 53 is indeed the Scirocco chassis. Type 53=Mk1, 53B=mk2, and 535=Corrado.
Drew
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Type 53 is indeed the Scirocco chassis. Type 53=Mk1, 53B=mk2, and 535=Corrado.
yay! i have at least one of all of those :? :lol: (don't ask why)
nice to 'see' you drew. :)
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Hey guys
This is my first post and I would like to say hello. My name is Peter and I live in Mississauga. I own a silver 1994 Golf TD. All I have on it is a K&N filter (which is nothing really :lol: ). I am about to start making an exhaust system from the turbo back out of .065 316L stainless steel. It will be TIG welded (I have a passion for welding) but I still have to get some SS plate for the flanges.
Anyways, best tank 45.1 US mpg, worst tank 33.8mpg, average since I bought the car (August 2003) 38mpg.
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HEY GUYS,
i'm new to the forum, but not new to vw gtd.
I have a 89' Golf GTD 2 doors that runs 6.6L/100km.
I just did some pump mods, closed wastegate and bov.
now it feels as fast as my G60 golf I had, but i don't think its faster! :( :?
You think i can get better fuel economy with a bigger exhaust, and how big?
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My 81 diesel just got me 4.223L/100km for primarily highway travel at an average of 95km/h.
And 5.2L/100km on a mixed 85km/h average through a hilly mountain (200km), and 105km/h for highway travel (400km).
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Or 5.72l/100km is 102.803577 rods per fluid ounce (http://www.google.com/search?q=5.72+liters%2F100+kilometers+in+rods+per+ounce&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a). I love the calculator too.
I want a speedometer that measures Rods per Hour. :D
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1988 golf gtd
JK engine converted to TD
modified,136hp on fly
best 4.8/100km 8)
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Hey guys,
need some advice....
what can i do to get my fuel consumption down?
will a better air filter make a big difference?
what's the best choice? and what about my exhaust, should i go biiger than stock?, i know it will help my performance but will it do any good to my mpg.
My car does 6.6L/100km. I would like do do 5 or something :wink:
and what about pump timing??
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It's a DI, even common rail, but just for comparison...
My diesel ride nets me 44L/100km. No, that isn't a typo, I did indeed mean to type forty four. :lol:
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1985 golf 1.6 NA (hyd) 4.6L/100 kms city - with light foot
injectors some ND 135 bar breaking pressure
pump redone by same oldschool veteran who did the injectors
5L/100 kms on highway doing 130 or 140 depending on the wind.
mk1 golf 1.6 TD (with nasty 11mm pump) and bosio SD274 nozzles and some petrol engine gearbox with tall ratios
6.5 or something litres/100 kms city
7 or 8 L/100 kms highway with punched throttle going till 6000 revs
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my new mk3 TD aaz just got 6.38l/100km on its first tank with me, gunning it around trying to see how fast it goes. it runs 205/45 r16's
my old '79 gld n/a 1.5:
best - 4.5l/100km
worst - 6.6l/100km
average - 5.4l/100km
with big exhaust, cold air intake, 185/60r14 sticky rubber and aggressive alignment.
cheers
aydan
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Ok 87 Jetta 1.6TD with mercedes 130 bar injectors, pump timing at 1.00, K24 with stuck wastegate (yeah it died last week :? ), fuel screw turned in a lot and LDA pin on the aggressive side, Falken Azenis RT615 195/60/14 tires (very sticky, not a hard compound) on Ronal R8 rims (pretty light I must say) and idle speed of 1100.
City: 8-10l/100km, it varies quite a lot depending on weather and my mood :P
Hyghway: 5,5-6l/100km @ 110kph
Yeah I drive it like I stole it in the city, that explains a lot :lol:
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96 AAZ Jetta - 42mpg US highway
92 wolfsburg jetta - 50mpg US highway
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I do 99.9% city driving in an '82 Rabbit, FF code 5spd, recently rebuilt injectors. In the winter I get 39 (US) MPG and in the summer, 43 MPG. I didn't seem to lose any economy with pre-ULSD 100% petrodiesel a year ago vs B20 ULSD today.
I do have a rear tire with a slow leak, so it's chronically low. One of these days I'll fix that and I bet that will net me a few MPG.
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Been a while since posting, but here goes.
90 jetta MF, pump mods (several), straight pipe, leaky tires(3).
Best: 4.1l/100km 1256km/tank(52l)
avg: 4.9l/100km 1000+km/tank(50 - 53l)
worst: 6.2l/100km 850ish /tank :?
All measured over a whole tank.
Generaly hohum driving, pulling trailers, pulling logs for firewood, collecting bales in hayfields ect., with the occasional jaunt to 6000 rpm at 24psi. (still pulls hard at 170, not tried more)
Ryan
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96 Golf III AAZ TD
Somewhere around 400k (cluster says 25k, but registration records show previous' at 400k 6 months ago)
four tanks worth so far averaging 39mpg (US) mostly city
with wobbly 195 60r14 tires and a bad wheel bearing
It's now shod with 185 70r14 (yes they fit) at 40 psi, new .270 nozzles, and the pesky wheel bearing has been replaced.
Hoping that I can maintain ~40mpg city going into the winter with the taller tires and a light foot - will update progress...
Kinda depressing to find that the AAZ MKIII's were about the worst (mileage-wise) Diesels that VW made, going by numbers from this thread mkI NA - 50mpg, mkII 1.6 TD ~45 MKIII 1.9AAZ ~42mpghwy... ALH TDI's back up to 45-50mpg. I had a 2006 jetta PD 1.9, and regularly got 52mpg (4.8l/100) highway, and it was a much heavier car... :(
Hopefully things will improve somewhat... However, it's still loads better than my previous saab, getting 10l/100 city.
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I have an 82 MK 1 Jetta. 4 door, ac, sunroof. Weighs about 2200 lbs. 5 speed and 330K miles on car/engine. Lifetime average approx. 42 MPG. I do flog the daylights out of it as I drive 110 miles from my home to Seattle at speeds of 70+ mph. Was on a site the other day talking about "hypermiling" and it had some tips. The usual suspects, tire inflation, remove excess weight, tune ups and synthetics plus it advocated several controversial methodologys that included coasting with engine off, minimal braking (consistent with safety) shutting down the engine and drafting. So being the idiot that I can be I tried them. Before anyone goes off half cocked the drafting was PRUDENT--maintained approx. 6 car lengths for 60 mph and was very attentive. Result for my typical commute went from 42-44mpg to 59! I thought I screwed up the math and did multiple rechecks and ran another test, this time 57 mpg. This is definitely slower than I normally drive but it validates the efficiency of these great engines.
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Another possibility is adding a belly pan to the underside of your engine bay to reduce drag. However that can be dangerous too as it can allow your car to "lift" like an airplane wing and lose traction at high speeds. But, apparently there are some worthwhile gains to be had there too.
Your Mk1 definitely has a weight advantage. As you noted it's barely over 2,000lb. The Mk2 gets closer to 2,500lb and the Mk3 and Mk4 are around 3,000lb. However the newer cars also usually have alloy wheels instead of steel, and larger rim sizes as well which improve economy (less weight = less rotational intertia). So obviously the best combination is R15 alloy wheels on an older car. ;)
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Hi,
I've often thought a belly pan would be a good idea, would help to keep the engine bay nice and clean too!
Any pics of installed pans?
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Another possibility is adding a belly pan to the underside of your engine bay to reduce drag. However that can be dangerous too as it can allow your car to "lift" like an airplane wing and lose traction at high speeds. But, apparently there are some worthwhile gains to be had there too.
hehehe... two less tires on the road = less rolling resistance :lol:
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However the newer cars also usually have alloy wheels instead of steel, and larger rim sizes as well which improve economy (less weight = less rotational intertia). So obviously the best combination is R15 alloy wheels on an older car. ;)
Ok, This intrigued me but, I am still trying to get me head around it. Bear with me...
In the case of the Carat / Eco I am building, Stock tire size should be 185/60-14, I already have 14" Alloys. I am keeping the ASF Transmission from the Carat bolted up to the Eco Motor (I think):
Code 1st 2nd 3rd 4th 5th R&P
ASF 3.45 1.94 1.37 1.03 0.75 3.67
If I get 15" Alloys I'd have to use 195/50-15 tires to keep my speedo accurate according to http://www.miata.net/garage/tirecalc.html.
So if I plug that stuff into http://www.scirocco.org/gears/ at 70 MPH I get:
185/60-14 = 2544 RPM
195/50-15 = 2551 RPM
Forgive me if I don't sound bright but, I am not getting the Inertia part... How would that play into it?
Would it be worth it in fuel savings over the life of the tires? Just for example comparison of prices / size from tire rack.
Michelin Pilot Exalto A/S 185/60HR14 $78.00
Michelin Pilot Exalto A/S 195/50VR15 $142.00
Fuzion HRi 185/60HR14 $41.00
Fuzion ZRi 195/50ZR15 $58.00
There is a much smaller price difference with the Fuzion but, does it save enough fuel over the life of the tire to justify the cost difference between 14" and 15"?
Or did I just completely over think the whole thing??
Or is the whole idea here to forget the speedo and get larger overall diameter for the tire and wheel? If I use a 205/60-15 tire on a 15" rim that gets the RPM down to 2343 at 70MPH. It also gets the tire price in line as well, as I can stay out of "V" and "Z" pricing.
Fuzion HRi 205/60HR15 $46.00
Michelin Pilot Exalto A/S 205/60HR15 $91.00
Based on that I can see where the fuel savings and higher MPG would come from lower RPM and probably pay for the tires easily.
I still don't get the inertia bit though :?
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The heavier the wheel assembly, the more its inertia resists the engine trying to speed it up (it also resists the brakes trying to slow it down because once spinning, it wants to keep spinning).
The lighter wheels and reduced inertia improving economy thus only have to do with accelerating, so you will see the biggest gains in stop-and-go city traffic. You will get (nearly) no gain in steady-speed highway travel -- once the wheel is spinning down the highway, it wants to keep spinning so the weight doesn't matter much.
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Ah Ok. Thanks, I get it now.
Ziptar <-- Physics Challenged
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Narrower tires can assist you as well, but there are some disadvantages to that as well.
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The 81 caddy with the Callaway conversion gets a combined average of only 38 to 40 mpg. I've played with the pump timing (.95 to 1.05) I've adjusted the fuel screw all over the place. I've done the gov mod and am using a green advance spring. This is all on a na pump. Has anyone switched from na to turbo then switched to a turbo pump for an increase in fuel milage? I drive fairly conservativly to keep the EGT's in check. Its been very frustrating to do all this stuff to the motor and only get 38 to 40 mpg.
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Have you checked the pump's internal fuel PSI, like hagar recommends?
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Narrower tires can assist you as well, but there are some disadvantages to that as well.
yea... the car will shimmy and drift at high speeds. driving my dads '02 saturn on the highway was great. mileage was probably better than my diesel right now. it seemed to shimmy around on the highway though... which i don't really like.
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Regular figures for my 90 Jetta TD are 40mpg (imperial) winter and 45 in summer. Just changing back to summer tires is worth 2 mpg.
A mile or 2 to warm up followed by 20 or so on the highway and another couple to get to work. 2 or 3 times an evening I have to start up and do a 5-10 minute trip. 80km round trip.
Best mileage was on a 1200km round trip last summer with a fair bit of highway and some stiff hills; I turned in 50mpg even with a/c going occasionally.
The '84 Golf n/a I owned for a while got 50-55mpg in mostly city driving, back in the days when diesel was 49c a liter.
There are a couple of things I could do to improve economy, i'll be posting some questions about that elsewhere- hopefully in the right place!!
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Ok,
One last look at this....
So if I already have 14" alloys, 15" alloys won't get me much.. In that case, I think I found the best way to go.
Going to a 195/70-14 tire would put my RPMs at 2337 @ 70MPH. Pretty good but, would make teh Speedo 8.8% too slow. I can live with that (or try a different speedo gear).
70s series tires are cheaper in comparison. Many brands can be had for less than $50 with higher tread life warranties. Closest Apple to Apples I can get..
Michelin Harmony 195/70SR14 Price: $86.00 (80,000 Miles Tread life Warranty)
Seems like cost, RPM, MPG, Tread life that would be the best mix.
I might be able to get a 205/70-14 on there and get the RPM down to 2286 but, I think that is pushing it.
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Another possibility is adding a belly pan to the underside of your engine bay to reduce drag. However that can be dangerous too as it can allow your car to "lift" like an airplane wing and lose traction at high speeds. But, apparently there are some worthwhile gains to be had there too.
Im afraid this is exactly the opposite to what is true(the lift part that is). Belly pans are usually used in conjunction with a diffuser to create downforce on race cars. This works on the principle that as the velocity of air increases, the pressure decreases. If you can "squeeze" air under the bottom of the car and keep the airflow smooth(this is where the belly pan comes in) The velocity will increase and the pressure will decrease which causes the car to be sucked down slightly. There is a ton more to this but I wanted to clarify that a belly pan is pretty much a free reduction in drag with no bad consequence provided it is mounted securely.
This is something I will be doing to my 84 rabbit before too long in my quest for better mileage.
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Im afraid this is exactly the opposite to what is true(the lift part that is).
http://www.hotrod.com/techarticles/body/hdrp_0609_aero_tricks_tips/index.html
Older cars with blunt front ends generated lift ... --air gets underneath and pitches the nose up. Pre-'68 Corvettes, old Cobras, and classic-era GT-40s were notorious for front-end lift at speed. But even modern, fuel-efficient, bubble-cars have lift, paradoxically caused by their very efficient wing-like shape.
Positive lift is bad; it makes a car float and hard to control, especially at speeds over 100 mph. It's far better to have downforce to push the car down against the pavement, increasing its traction. "It is important to be able to steer the car at the speed you want to run at,"says engineer Chuck Jenckes. "You don't want a buoyant car."
Ok, so we don't drive our cars 100MPH, but the possibility of excessive lift is there. I don't know how pronounced it is on our old VWs or if it's dangerous or not... just sayin' be careful, don't sue me if you crash. ;)
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lol... introducing the all new tailwing mod for your jetta! take corners at extreme speeds :lol:
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I may have misunderstood you the first time around. I thought you were saying that the addition of a belly pan would produce lift. I dont think this is true in any circumstance.
I agree that most street cars, especially older ones are subject to a lot of lift at high speeds. Air dams, splitters, bellypans and diffusers are all tools to reduce, if not eliminate this.
From the testing I have done personally, I have found that there are a lot of gains to be had in gas mileage by reducing drag. The first place I would start(since its the easiest) is to reduce the grill opening to the smallest size possible while still providing enough cooling. Start by blocking a little at a time till the car starts to run warmer and then unblock a little from there. Wide masking tape is your friend here. Another place for improvement is to encourage the air that does have to go through the radiator to exit the wheel wells, or if you dont care about looks you could vent through the hood or behind the rear of the front wheelwells. This can be combined with a belly pan to keep the air that does go through the radiator from going under the car and producing lift. Care also needs to be taken on the front end of a car to make sure too much air is not getting under it. Some air does need to get under the car but the ride height requirements of a street car will take care of this. An air dam on a rounded front car and/or a splitter can make the bumper or air dam more efficient by keeping the air that hits the front of the car from spilling under the car. It helps encourage it to go over or around the car where the panels are smoother. Lowering the car can also help reduce frontal area. These few things can go a long ways in increasing gas mileage. I am out to see how much on my diesel rabbit. It was good for over 10 mpg on the highway on a cavalier.
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There is alot of good info about MPG related things on this site, granted it's devoted to Geo Metro type cars but, allot of theory and experiments with general ideas.
http://www.metrompg.com/
looks like a sedan has less drag than a hatch and changing the shape helps somewhat. http://www.metrompg.com/posts/boat-tail-prototype.htm
(http://www.metrompg.com/posts/photos/golf-jetta-wake-s.jpg)
This makes me think about taking an old rabbit (golf 2might be better) and aero modding it. http://www.1989geometro.com/. Wonder what it would do with a 3cyl TDI in it.
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With diesel bumping upwards of 4$ per gallon this topic is close to my heart and wallet. I have been tinkering with tires, speeds,weight reduction, synthetics etc. The obvious solution--my lead foot--has the most impact, but I am curious about the drag issue. Does anyone know what the Cd (co-efficient of drag) is for a MK1 Jetta? More significantly at what speed does the drag become a big factor (parasitic drag?) I think I am bumping up against simple physics on my quest to increase mileage.....
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from the information I found it appears that the mk1 jetta has a drag coefficient of 0.43 while the mk1 rabbit/golf has a Cd of 0.42. This was the trend from the different places I looked. The jetta has a slightly higher drag coefficient than the hatchback golf.
I am going to go out on a limb here and guestimate that aerodynamics will start to make a difference in fuel economy at 40-45 mph. Im really not sure about that though. My biggest indication of this is not real scientific. Drive with the window down and put your open palm into the wind and feel the resistance then you be the judge.
My rabbit project is still rolling on still. I have a few ideas so far but I have to wait till I get the engine back in it to get a baseline mpg number, then I will build the belly pan and diffuser.
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Is buying a year's supply of fuel in the early fall when it's cheap (before winterization and the heating oil demand) advisable? I know you'd have to add some kind of anti-gel agent for the winter but it would take a lot of anti-gel additive before you stopped saving a ton of money.
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i would just add the power service cetane booster & anti gel. the cetane boost will probably increase your mileage enough to make it economical :)
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91 jetta big bumpers 1.9TD
i can squeeze over 50mpg outta my ride if i grandma it, thats over 700 miles on a tank running 5% biodiesel
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I vote for a new group brain storm project.
With the price of diesel and home heating oil going through the roof, and diesel looking like it is going to hit $4.00 a gallon, I suggest we figure out a Milage Master potential build up.
I think the primary goal should be to squeeze out the maximum MPG possible at highyway speeds of 60-70 mph. 0-60 times would not be relevant. A car built for commuting. Can 60 MPG be obtained?
We could look at various engine efficencies and modifications, to tires, to transmission modifications. Areodynamic changes, ride height changes, weight reduction, etc.
NA or TD? TDI or IDI? Perhaps one of each?
Team IDI vs. Team TDI ??
Theroreticle into practicle into cost savings for all of us.
Anyone interested? Perhaps we can start this as a new post.
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good plan
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Kind of a different train of thought. I still plan on finishing my build up for power, but economy is getting very important with fuel costs so high.
I think that as a group we should be able to produce a result that gets far greater mpg than is now achieved.
Just in the engine alone there are countles mods. Nozzles, breaking preasure, timing, ceramic coatings, friction reducers, porting, etc....
The transmission holds all kinds of gear variations.
I am sure most of the research has been done on this forum already. It was just aimed at a different result. Power.
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from the information I found it appears that the mk1 jetta has a drag coefficient of 0.43 while the mk1 rabbit/golf has a Cd of 0.42. This was the trend from the different places I looked. The jetta has a slightly higher drag coefficient than the hatchback golf.
Do ya have sources? I've heard it was the opposite.
I think the primary goal should be to squeeze out the maximum MPG possible at highyway speeds of 60-70 mph. 0-60 times would not be relevant. A car built for commuting. Can 60 MPG be obtained?
Bone stock w/ a 3.89 R&P/.71 OD/155/18R13s we can hit ~60mpg at a little less than a 50mph average speed on open freeway/highway if we drive it right. Any better requires mods for better aerodynamics.
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So what do you think the upper end is for MPG?
I am interested in the MPG rate for around 65 mph. If I drive much slower then that on I-95 I will get rear ended.
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Subsonic, I like your idea of a competition/build. It would seem that there are enough gearheads here who could contribute to the idea. It seems me that we are seeking to get better MPG at realistic freeway speeds. (65-75mph) Courtesy would dictate that flowing with traffic would be the first benchmark to attain. The idea of setting up a competition with our TDI bretheren could be an inspiration for workable ideas.
It would require some baseline rules and disclosures to benchmark. I think the TDI club website has something along these lines but we might be able to raise the bar. My personal best was with a 79 Rabbit and a Callaway turbo driving eastbound across South Dakota in the winter with a tailwind and averaging about 55 mph--I got 69.8 MPG. I'm sure that there are some who have done better. Just my two cents....
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Great idea- for inspiration check out VW's factory effort, the 1 liter car-
http://www.seriouswheels.com/cars/top-vw-1-liter-car.htm
It looks like that ride is pushing 300 mpg.
I would maximize my mpg if I cut the top two thirds off of my westy, which normally has the drag coefficient of a small office building.
Short of that (actually taller than that) I will play with a teardrop cover for the luggage cap, and eventually make curved double doors at the rear that give it more of a fishtail.
I would be tickled with 35-40 mpg.
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I am not looking to go off site with this, or have a mine is better type of thing. Just group research, testing with posted results that we can all use. We can do what auto makers can't because of scale of economics. We can have if we choose to, a car that gets outstanding highway mileage at the cost of perhaps other performances losses that a corp. would find unacceptable for general sales. I really do not know what type of diesel engine could get the best MPG.
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"Back in the day... " of the first farcical "Arab Oil Crisis", 1973-74, we in the U.S. were told by the feds(Same administration that claimed, "Your President is not a crook!") that 55mph is the point at which the average passenger car's drag from tire rolling resistance was surpassed by the drag from aerodynamic forces.
That said, the average VW R/J/S (MK I series) of the mid 70s-early 80s was still a lot better aerodynamically, than most of the porcine Detroit offerings, so that 55mph mantra may or may not have been true for 'us'.
Our then new, but broken-in, '81 Rabbit 5-door consistently bettered 50mpg on highway trips(70-75mph cruising speeds) even with 4-5 pairs of skis on the roof rack; tips to the rear for best efficiency, please.
My '79 Dasher 1.5L n.a. diesel 5-door sedan did an all-time best of 57.8mpg on a trip, when new tire imbalance limited the practical cruising speed to 60mph(3000rpm in 4th gear). That was with 4 adults on board, and every inch of the car's cabin & trunk & a huge Thule "Pod" on the roof crammed with traveling/camping gear(total loaded weight est. c.3300lbs). That is not too far off the Federal noise about the magic of 55mph, and IMO is a great tribute to the aerodynamics of the Thule "Pod", not to mention our trusty IDI clattermeister under the hood.
Previous high fuel mileage had been 54.6mpg, done at my normal cruising speed of 70-75mph(on relatively level ground!). Even when pulling a trailer with my '80 Dasher 1.5L n.a. diesel station wagon (total weight: 4650lbs!), the highway mileage has never dropped below 33.6mpg.
Side note: A couple of months ago, I wanted to see what our '01 Saturn (1.9L 16V gasser w. auto trans) coupe could do at a (mostly)55mph cruise-controlled pace on I-5: it came out @ 42.3mpg for a 300-mile segment. That says something for better aerodynamics, as well as the validity of the 55mph claim, since this Saturn's 'typical' highway fuel consumption is 33-36mpg(@ 70-75mph). OK; now back 'on topic'...
So, re. the VW diesel-powered vehicles, it seems to me that the earlier suggestions re. cleaning up the cars' aerodynamics with spoilers & belly pans, as well as trying to minimize rolling resistance, while utilizing turbos, intercooling, free-flowing 2.25-2.5" exhausts, careful pump tuning/timing, and 55-60mph cruising should easily get the lighter Mk I cars well into the 70+mpg range, or maybe even higher with some trick gearing or extra cam & headwork. Maybe the cleanest body envelope to start with would be a lowered '74-'76 Scirocco, and build from there with all the tricks. Could be fun.
Seems like this site has some sharp thinkers & tuners among its frequent contributors. It will be interesting to see what emerges as the pump price of Diesel no.2 edges toward $5.00USD per gallon.
Back to lurk mode. Shutting up!
J.R.
SoCal
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It will be interesting to see what emerges as the pump price of Diesel no.2 edges toward $5.00USD per gallon.
Aside from that cost being reflected on the grocery store shelves.
First thing you'll see is the masses lamenting that Detroit didn't spend the last 15-20 years focusing on SUVs with giant Leather Lazy Boy Recliner like interiors with all manner of needless/nuisance electronic gadgetry and that the U.S. Government made importing cars like the Volkswagen Lupo 3L TDI (http://www.vwvortex.com/artman/publish/printer_319.shtml) with its 78 MPG impossible via cumbersome and pointless emissions and crash test requirements designed to protect the big three.
Just as with the fuel crisis of the 70's The big three will take years to turn production around, make some flops (ie: Oldsmobile 5.7L Diesel).
$5.00 a gallon should also bring alternative fuel into common use. Up to now it's cost has been a stumbling block.
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So what do you think the upper end is for MPG?
I am interested in the MPG rate for around 65 mph. If I drive much slower then that on I-95 I will get rear ended.
Depends on how much you'll do. If ya do like this (http://www.gassavers.org/showpost.php?p=74110&postcount=167) and go w/ taller tires/wheels, I'd say ya could do an easy ~80-100mpg@65mph. Less extreme aero improvements will result in smaller mpg increases. Rolling resistance, aero resistance, and gearing will see greater gains than fiddling w/ the engine base on what I've read.
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Anyone know aerodynamically what the difference between the small bumper and big bumper numbers are? is it very large drag wise?
Getting ready to send the big bumper car to the scrapper but, maybe I should hang onto the bumpers. Is it worth the cost of getting them painted to match?
On that note, I was planning on saving the stock springs from the big bumper car to swap onto the 89. The 89 has Eibach lowering springs, which i normally hate.
Now I am starting to think leaving the lowered springs on and a big front bumper might give me better MPG, less frontage area and air under the car.
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Larger exhaust seems to be a factor in better fuel economy maybe 20% or so :shock:
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I am interested in the MPG rate for around 65 mph. If I drive much slower then that on I-95 I will get rear ended.
I should also add that when i say a little less than 50mph average speed I mean door to door average speed. That includes ~10-20 miles of stop/go in the city, ~20-30 miles of highway, and ~55-65 miles of freeway. My speed depends on conditions. The lower my average cruising speed is w/o having to excessively brake while optimizing engine efficiency, the better my mileage is. That being said, I tend to average ~30-35mph in the city, ~45-55mph on the highway since traffic is generally sparse, and ~55-65mph on the freeway depending on grade/winds. One section of the freeway portion is a significant uphill grade into constant headwinds. Here I can tuck in behind one of the slower semis and go ~45-55mph. On the way back, I'm going downhill w/ a tailwind and pass semis at a ~60-75mph average.
To calculate your average speed, you take your distance and divide it by the number of hours you spend getting where ya went. Unless you literally fire up the car and get on the freeway, and your destination is literally right off the exit, I doubt you actually average 65mph if you stick to a crusing speed of ~65mph. The best piece of advice I have about mileage is that keeping it under 65mph is best, and the slower you go, down to ~20mph average speed, the better your mileage can be provided you can optimize engine efficiency and can stay off the brakes.
Anyone know aerodynamically what the difference between the small bumper and big bumper numbers are? is it very large drag wise?
Now I am starting to think leaving the lowered springs on and a big front bumper might give me better MPG, less frontage area and air under the car.
I'm pretty sure the difference between big and small bumpers are insignificant. Lowering otoh will reduce reference/frontal area like ya mentioned, and more importantly imo, reduce the amount of chaotic air flow under the car.
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Great! I am growing to like the small NA bumpers.
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i am running 185/80r13's @ 35 psi, cruise at 60-65, shift on the shift light, 95% highway driving w/ no other mods and have pulled in 59 mpg but usually it's between 50-55. will be putting an exhaust cut out on soon w/ no muffler for the highway and cruise control and will be doing the pump mod on the spring soon.
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Well, if I ever get the Jetta on the road, I plan to play with some underbody aero mods. & I already picked up a GTI air dam (primarily to cover the slightly mangled radiator support) which should also help. Then to pull off the luggage rack on the trunk and perhaps add a small spoiler to the rear (the sort that goes on the vertical part of the trunklid, rather than on top I think).
This should be handy as well...
http://www.instructables.com/id/Measure-the-drag-coefficient-of-your-car/
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I have a 94 1.9 IDI (AAZ) and have switched my trans over to Lucas full synth 75w90, done a couple light pump mods (boost limiter switch and re-wired the timing retarder solenoid(for emissions). Still need to do new rear bearings and I drive mixed city and highway at 65mph. I can and do pull a solid 950kms to a tank, and never really pushed it too deep into the red. Oh yeah tires are at 44 psi all around. And I have the CHE transmission. (60mph, 2600 rpm)
I found this car last december with 60,000 miles on it! bought it for 3800, and it had already had the TDI crank mod done!
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Sounds like you got a good deal and a very healthy motor.
My car (91 Golf NA) with a Giles pump, AGS tranny and stock everything else gets me 1000 kms / 46 liters usually if I drive 110 on the highway. I haven't done a full city tank yet. My motor has 250 PSI all across the board. It will be getting replaced soon.
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yeah the only thing that came up recently is it got hard starting if it sits overnight. I am still diagnosing, most likely a glow plug, but when I shut it off their is a bubble that pulls back on the fuel supply line, almost line a back vacuum is backsucking. I a have replaced everything under the hood for lines, and the the lines to the tank are good, pulled out the fuel pick-up, clean and smooth. new filters, and all. there are two little lines goin to the pick-up in the tank. in front of them look like 2 little check valves. Is that what they are? Trying to figure this out. I even took off both banjo fittings on the pump and re-annealed them.
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good god 72 cents a litre in 2004 (i only read the first post)
and we're paying $1.50!!!
diesel came DOWN to $1.36 the other day i was so surprised i got a full tank. Still cost me about 70$ though :(
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bump ;D
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wow! it's been so long. kind of weird to be reading something from so long ago. i have a few ideas for economy but it will take some bodywork and i don't have the time right now. i've now got 2 kids. i avg 45 mpg.
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my new mk3 TD aaz just got 6.38l/100km on its first tank with me, gunning it around trying to see how fast it goes. it runs 205/45 r16's
my old '79 gld n/a 1.5:
best - 4.5l/100km
worst - 6.6l/100km
average - 5.4l/100km
with big exhaust, cold air intake, 185/60r14 sticky rubber and aggressive alignment.
cheers
aydan
UPDATE - of my old figures - its been 2 years!
My '94 mk3 with aaz now gets between 5.2-5.6l/100km every week doing 900km, 3000rpm cruise.
New car - '91 cabriolet with 1.5D (sooo slow) gets 5.7-5.9l/100km with reco'd engine, good injectors, and AUG trans.
My '77 LS Golf gets 10.5l/100km (1.8 8V gasser with Dellorto carb and euro cam) but its fast :-)
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Pump timing seems to have quite a profound effect on mileage. On my 93 Passat Eco-diesel, bumping the timing up from .95 (I think it was) to 1.05 took me from 47 mpg to 53.
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I'm going to make myself unpopular now... :'(
I see so many definitive figures above for mpg, here we have 48, there we 53 now we have 59...
All as good as meaningless I'm afraid, and I know your Replys will all be screaming from the rooftops that you 'know' for sure it 'did' 45, now it 'does' 53, or 'was' 51 now 'is' 55... and you drive the same journey every day and fillup at the same pump at the same station, and the tank brims and the nozzle cuts out at exactly the same point and you drive the same and the weather's the same day in day out ....
Don't bother, because without one of these, which shows what really happens from day to day, from season to season and from Mod to Mod, over several thousand miles, I'm not listening...
(http://wiki.club8090.co.uk/images/Consumption_G208THV_03.jpg)
As you can see, a definitive figure always has a quite considerable band of variance, even for the same journey... manufacturers figures are quoted for 'very, very specific and accurately controlled conditions' - we cannot emulate that.
Note the above graph covers 7,000 miles or so... now we can slowly see what sort of true mileage we are getting (currently I'd quote 23.5 +/- 1.5), and how varied fill-to-fillup (accurately brimmed) mpgs can be.
Blue = fillup to fillup
Yellow = Average of last 3 fillups
Pink = MPG to date (total miles/total fuel to date)
A picture's worth a thousand words, so lets have them... or stop quoting mpgs to within 1 mg and start saying was about 53, now about 55 (+/- 2).. it's easy for the error band to overlap.
Mr Un Popular :)
PS. UK Statute miles, UK Imperial gallons (proper ones), odometer mileages corrected by GPS factor (to account for tyres and odo errors)
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yeah, ok. but what if i say that in 12 months i covered 55,000km, and over that whole perieod, i see a consistent trend of my economy increasing (i.e getting better) as i make modifications to the car. for the first 2 months i owned my car (before any mods) i was getting about 6l/100km, and now i'm getting about 5-5.5l/100km, 2 years and many modifications later (none of which were particularly economy oriented, everyhting i have been going for was for increased performance :-) )
:-D
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Harry,
You make a very valid point about consistancy. I fill up to the litre when I fill up at the pump, but my results will be skewed somewhat. I changed tires a few times, had a slow leak issue in 2 tires, and I have loaned my car out to my brother a few times. The other thing is, I don't really care how good of fuel mileage I am getting, as long as it isn't as bad as my jeep was (something like 14-16l/100km).
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Figured I'd pull this back up......and brag a little ;D
Best this summer was 46.65mpg on July 17-18. 525 mile round trip with 4 people and lots of gear, I filled up at 420 miles and it took only 9 gallons filled to the brim!!!!
It helped that I was following a '84 vanagon waterboxer and didn't have to keep it floored, speed on the flat was good at 55-65mph, hills slowed us to 45-50.
Earlier this summer I made a 200 mile round trip with a group of other cars......me being the slowest ::). I was running full power without holding the egt's over 1100F on the hills and cruising at 70ish on the flats.
That trip was only half the tank and the for the rest I drove normal. That tank still got 45.5mpg :D
Normal driving for me is to accelerate shifting at 2500-3000rpm depending what gear it's in and staying mostly out of the smoke range and letting it slow a little going up hills. Cruise is 55-65.
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Ok so my last fill up was when I got 46.65mpg in my last post and I got to fill up with good ol' #2 diesel ;D.
So today I filled up again after 400something miles (I forgot exactly) and calculated 47.2mpg or 4.98L/100km......or 56.68 imp mpg. I'm not bragging :D.
I wish #2 was easier to get :(
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Wow, this one's dug up from the depths.
Thought I'd contribute because I remember reading this thread years ago before getting my rabbit.
Car is a 81 1.6NA with a FF 5 speed, 4 door, aftermarket sunroof, AC but been disconnected for a couple years (though the weight is still there). I drive around town, then 300 miles round trip to the city to work once or sometimes twice a week. I do about 12-1500 miles a month, always fill up at the exact same place cause it's a hassle to track down diesel in the city, so I fill up on my way down, and usually drive out the balance around town, then refill on the way down again. Synthetic in the case and tranny. I drive 60-65 everywhere that isn't a school zone, live in eastern NY so it's hilly but not mountainous. I'm not aggressive, but on hills I have it all the way down very frequently, and occasionally have to pull 4th.
I run my mileage at every tank just to be alert to if something changes drastically, but don't tally it long term. The car was getting 42-44 mpg (every tank, never more or less so long as the AC was disconnected except for one crazy trip back from Michigan with a huge storm at my back for 600 miles). Last winter I did the headgasket and timing belt, and retimed from somewhere in the mid 80's to .95. Car now gets 47-49 every single tank. Doesn't seem any faster, slightly clackier at idle when cold, but every single tank I'm seeing about 5mpg better. I've owned this car for 4 years and about 50k now. Hope it helps.
Luke
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Static timing does make a huge difference. My Passat Eco when from 47 to 53 miles per imperial gallon by advancing the timing from .85 (I think, whatever the factory eco setting is) to 1.05.