SolvedBEST CAR FOR A, B, C CLASS EVENT

Hopefully they'll give something faster this code.

For the purpose of farming drag races you just want the car with the highest acceleration, and a good top speed - handling isn't much of an issue.
for the games you can start with/can buy with In-Game Cash my list would be :

E class - Volkswagen Scirocco (best acceleration of all starting cars, 3rd best top speed, the Dodge challenger and volkswagen R32 have a little bit more top speed, but slower accelleration)
D class - Audi RS4 (best aceleration and speed for it's class, at least when it comes to cars you can buy for in-game cash.)
C class - Audi Quattro 20 V (in-game cash car with thebest acelleration together with the Audi TT RS Coupe, but the Quattro has a bit higher topspeed and much better handling)
B Class - Either the Lamborghini gallardo spyder or Dodge Viper srt10 (i went for the dodge viper since the best A class car is also a Lamborghini)
A class - Lamborghini Murcielago Roadster hands down. (best accelleration/ good top speed and decent handling)

it's also worth looking into setting up bot-a-lot for drag races, or combine it with sandboxie so you can race 2 accounts against each other, just make sure your main account has the fastest car, so it will continuously win gold cards. ever since events have been changed so that different ones are class restricted the reward chance for ultra parts isn't that great anymore, but letting It run all night should net you at least a bunch of pro (3 star) and a few ultra (4 star) parts.
Selling all the 1/2 star parts and skill mods you get will also turn a small extra profit on the in-game cash you'll be making this way