When you first start a profile on PGR3 buy the skyline, it is hands down the 
best starting car in the game, you can keep using this car for a long time 
before you need a new car, and for that I suggest the supercar prototype, (i 
think thats what its name is) its a faded blue car that looks somewhat like the 
Saleen S7, after that car you will get enough money to fund a massive 
collection, I already unlocked 6 garages! each with more cars than the last.