Great idea for people with low end computers, but usually this doesn't happen, for now take some parts off.
Polys are basically what give a car its dimension, cars would look like trash if they had a low amount of polys.
Cars would look like rigs of rods but its worth it if you don't have more than 4gigs of ram in your system.
Since the physics simulation is not run on the actual mesh of the cars, but the beam/node structure decreasing the polycount wouldn't give much of a performance boost. Probably won't be even be noticeable. I don't know what's the exact poly count of the models but they don't look too much.
Vehicle polygon count has almost nothing to do with performance. Most of the lag is from either vegetation shadows (graphical) or the physics themselves. Low poly cars would not help.
omgz plz link to teh mod downlooodd!!!!11!! dis is amazein i wont to pleh it haw i spawn new carrrr That is your typical forum noobdiot.