Author Topic: How much does winter impact on fuel economy? (Read 4953 times)

srivett · « **on:** January 09, 2005, 06:58:02 pm »

Hi again.

I know it really hurts gas engines, how about diesels? Has anybody kept good enough records to notice a difference on their VW Diesel?

Cheers, Steve

ricosuave · « **Reply #1 on:** January 09, 2005, 07:07:33 pm »

i dont have my records in front of me but...

i find that i get about 75-100km less per tank in the winter.

jtanguay · « **Reply #2 on:** January 09, 2005, 07:38:33 pm »

i think the reason gas engines hurt so much is because the ECU goes by air intake temp. Really cold means it can throw in more fuel. So your car kinda runs better but taking more fuel. Diesel isnt affected much by the cold weather except maybe better combustion? I think my diesel runs better in winter than in summer (except those really hard start ups!) I also think that using the cold start lever affects it too... If I forget to push it back in it takes more fuel to run, and that is the only case I can think of that a diesel would take more fuel. Adding the fact that you have to wait for the engine to warm up doesnt help either. In summer I start it up, and drive right away, but not in winter(Few minutes idling takes fuel you know

)

Someone must have a better explanation than I do though... Does winter somehow affect how much fuel is consumed other than what I have described above???

jtanguay · « **Reply #3 on:** January 10, 2005, 11:42:33 am »

oh yea i forgot that fuel temperature somewhat affects mpg... That would decreate mpg by what.. 1-2 mpg?

jtanguay · « **Reply #4 on:** January 10, 2005, 02:15:26 pm »

wow... I never thought about the drag coefficient... I suppose waxing the car might help combat it? hehe

Of course winter will bring less mpg for us dieselers, but certainly not as bad as one of those gas 'guzzler' cars.

Man would I love to have a TDI engine on some of those cold days... My car blows a ton of smoke now at startup so I'm pretty sure one or two glowplugs are busted

MayorDJQ · « **Reply #5 on:** January 10, 2005, 02:29:59 pm »

Probably the biggest cause of lower fuel mileage with a Diesel is that the fuel must be "winterized", which lowers the BTU's of the fuel. Using an additive like Powerservice or Stanadyne will help bring the numbers up. I'm sure the extra electrical load of the heater fan, rear defroster, headlights, etc. reduce the mileage a little bit also.

TDI's suffer in cold weather as well as IDI's. Mine goes down to about 45mpg in winter compared to 50 in the summer.

chrissev · « **Reply #6 on:** January 10, 2005, 02:41:46 pm »

Quote from: "srivett"

Hi again.

I know it really hurts gas engines, how about diesels? Has anybody kept good enough records to notice a difference on their VW Diesel?

Cheers, Steve

one problem I have is i need to rev the car (or idle it) for about 3 minutes after start up before I can drive it. Otherwise it will buck and hesitate too much. In the summer it's just turn the key and drive away. I know this uses extra fuel, especially since I can see the smoke coming out the back for the first 2 minutes of idling after cold start up at below 0 degrees.

RAMMSTEIN · « **Reply #7 on:** January 10, 2005, 04:01:42 pm »

Quote from: "jtanguay"

Man would I love to have a TDI engine on some of those cold days... My car blows a ton of smoke now at startup so I'm pretty sure one or two glowplugs are busted

You wouldn't like to have a TDI in winter, because it takes an eternity to warm up!!!!! :roll:

I go from the high 60's (in summer) to the low 50 mpg in winter....not good. :evil:

jtanguay · « **Reply #8 on:** January 10, 2005, 07:33:23 pm »

could the low mpg also be affected by the TDI ECU??? Maybe mechanical TDI would work best

RAMMSTEIN · « **Reply #9 on:** January 10, 2005, 11:27:38 pm »

Why, the timing is the same?

The fuel is different and the climate too.

Plus the added drag because of numerous factors.

That's enough to drive fuel economy south (or north, whichever suits you best :wink: ).

jtanguay · « **Reply #10 on:** January 11, 2005, 12:50:42 am »

well whenever its electronic... somehow the electronics always put more fuel when the air is cooler... (this might also explain why TDI's dont smoke... the ECU wont put in more fuel than will burn into the engine

)

crazybushman · « **Reply #11 on:** January 12, 2005, 02:02:58 pm »

My mileage in my 1985 TD Jetta has gone from 50-61mpg summer to 37-43mpg winter..... Those are imperial mpg too... What do you experts reccomend? I'm running Howes additive, cruising at 110kph on the highway (sometimes 100 when I'm not in a rush), during the summer, I go 120-125 and get better mpg :?: :?:

What would happen if my intercooler had a hole in it? I see some oil coming out from the bottom of the tmic, I'm guessing a hole, and ever since I installed it, my mpg have been dropping.... (except for the first road trip which was 61mpg), hmmmm.....

Cheers!
Tyler

chris-pl · « **Reply #12 on:** January 13, 2005, 05:59:51 pm »

before mods
summer 6.2/100km
winter 6.5/100km

jtanguay · « **Reply #13 on:** January 13, 2005, 06:31:42 pm »

maybe you should try a water intercooler setup. With a big intercooler you loose some psi. Could be piping too, any sharp angles are bad for airflow.

Anyone have experience with a water intercooler? I'm thinking of getting one

chris-pl · « **Reply #14 on:** January 15, 2005, 07:03:04 pm »

mileage after mods
winter 6.43L/100KM