here are the cars I used so far, they are not necessarily the best:
C4-Lancia Delta
B4-Range Rover Sport
A7-Alfa Romeo Brera
A6-Audi TTS
A5-Dodge Charger SRT8
A4-Audi RS6 Avant
I might use the Audi R8 Spyder I won in the casino for the A2 championships, except im struggling to pass my A3-A2 licence tests. and if the R8 isnt any good, ill just buy a Ferrari 458 (or another car) instead. but first I need to pass the stupid and pointless license tests. also for some reason, I couldnt pass the "Fast Corners" test in cockpit view which i normally use but i passed it first time i did it in chase view (which i only use in GTA 4). im going off topic now so ill end this post now.