I believe Malone played with one and did some calculations on what can be done to a smart car.
OK, I chipped a 0.8L 3cyl common rail diesel (at present the only engine option that's available in Canadian Smarts) about a year ago. At best without smoking too much, the gains are 41HP (stock) to 52HP (chipped), and 74lb-ft (stock) to 90lb-ft (chipped). Some tuners advertise an increase of 20HP or more but G-Tech results confirm that these estimates are exaggerated.
Stock acceleration (41HP) is advertised @ 19.8 seconds if I remember correctly. I forgot to time acceleration after the chip was installed but it feels more tolerable... my rough guess would be 14-15 secs. Not fast by any means, just more tolerable. 1/4 mile times are reduced frpm high 20s (stock) to mid-high 19s. Yes, only 1 to 1.5 second shaved off, even if the Smart smokes quite a bit. The trap speed at the end of the 1/4 mile is 70 MPH (112 km/h) vs. stock 65MPH trap speed. The 0.8L runs out of steam in the top end.
CMAP = Tuner in Calgary (I forget who).
VMAP = Tuner in Vancouver (flyingtiger.ca - NOT me).
Mozsimo = Tuner from Spain if I remember correctly.
* HorsePower: 1st - Mozsimo (49.6), 2nd - CMap (47.9), 3rd - VMap (46.9), 4th - Stock (36.0)
* Torque: 1st - Mozsimo (71.5), 2nd - VMap (69.3), 3rd - CMap (67.6), 4th - Stock (56.2)
* 1/4 mile times: 1st - VMap (19.334), 2nd - Mozsimo (19.768), 3rd - CMap (19.881), 4th - Stock (20.946)
* 1/4 mile trap speed: 1st - VMap (71.38), 2nd - Mozsimo (70.80), 3rd - CMap (69.01), 4th - Stock (65.44)
The HP and Torque values above are net numbers from G-Tech, not precisely engine or wheel horsepower. These results were taken by someone else, so I don't have G-tech results with my chip.
The Smart CDI's turbo is not controlled by the engine computer - it's only controlled by a mechanical wastegate like the IDI/VW TDs. The wastegate actuator is adjustable but there isn't much room for efficient boost increase... adjusting the actuator rod is mainly ideal for controlling boost spikes intially caused by an increased surge in fueling (from a more powerful fueling chip) rather than adding performance, AFAIK. That, and the inability to take VAG-COM logs, is why we don't need to bother making fully custom tunes for individual Smarts. We sell mostly canned tunes only. Smarts are also not very popular here on the west coast compared to Quebec/Ontario.
The 1.6TD's turbo is quite under-used (~10 PSI stock) so they have plenty of room for more boost while staying within the turbo's efficiency range.
A couple years ago I was excited about the Smart and thought of trying/buying one, but after playing with a customer's Smart, I chose to stick to VW diesels.
IMO the 1.6TDs are more economical and more tunable. New Smarts are $18k CAD last I checked, and they have a rather poor fuel economy/performance ratio compared to VW TDIs. 50-55 US MPG are commonly seen by Smart owners, with some hardcore drivers achieving 65-70+ US MPG (driving really really carefully). That's not impressive considering their size.
VW's 1.2L 3 cylinder "3L" with aluminum block in a MK1 Rabbit will have similar or better fuel economy and significantly better performance potential. Not to mention that including importing a 1.2L engine from Europe and swapping it in, it'll still cost half that of a Smart, so the Smart does not really pay for itself. The 2 seats, small cargo, and lackluster performance kills the deal.
A 1.4L 3cyl would also be ideal if we want a little more performance (there are 1.4Ls with 90HP stock and maybe 120whp after a little tuning) without hurting fuel economy much. The VW cars also have great aftermarket support (low cost suspension, lots of wheel options, seat options, lighting, etc.).
In conclusion, the Smart is just a novelty car IMO, although I respect them for adapting more people into accepting diesels.