Go to "seasonal events" and select any of the bonus races. If you go up to restrictions it'll tell you what car you need for it. I didn't mean to come off as harsh but it's laughably easy to make money with bonus races. If you buy the iMiev and C30, put another 50-60k in parts, you can do both races and get 800k+ (I believe.) Also, just upgrade a car with 700+ hp, then do the supercar festival daytona loop in the professional series, for 20k every 2.5 mins.