How many cars do you have?
What driving do you prefer?
Buy a premium road car and fully tune it into a racing machine. Like a Ferrari Scuderia or a Lambo SuperVeloce...
get gt500 and do the b spec online seasonal i get 20million by 3hours XD
wrapture186. anything.
Do the Spa seasonal, Buy the Jag and Ford $20mil cars, then the Lamborghini for $15mil. This will take about 4 hours more. Then the F1's if you still want to. Then worry about cars that cost <$10mil.
You can get the Ferrari and Lambo from a '67 ticket. Only $20 mill car worth buying in my opinion is the X1.