Cars I got to work:
Knight Supra-deluxo
mclaren f1 le mans-hotring racer
lexus gs430-bloodring a
mercedes benz slr mclaren-sabre turbo
aston martin vanquis-esperant
lamborghini diablo-infernus
ferrari f50-cheetah
mazda rx8-blista compact
saleen s7-bloodring b
ducati 996-pcj600
The only slowdown in the game is near sunshine autos because I have the supra, benz, and mclaren f1 all there and they are very high polygon counts.
Other than that the cars all have working colors and handling files to match realistic values for the cars. The only one that didnt come with a handling file was the saleen s7 but I just used the banshee's handling file for that and it worked perfectly. Also the ducati and the infernus handling I kept the same because they are already pretty darn good.
*A little hint is if you want to have a car with a high polygon count then repalce a car that does not respawn like the ones at the sunshine autos or garage near downtown...that way when you drive the car you wont have any slowdown.*