If anyone wants to test any cars before buying them.
Go to freeplay, choose any rental car. Then go to buy car and follow through all the screens as if you are going to buy, until you get to the screen asking if you are buying with credits or tokens. Once on that screen back out all the way back to the lobby, you are now in the car you wanted to test.
There are 7-8 (i think) achievements you can unlock doing this.
The only problem in doing this i found is, i now need both old F1 cars, indy car, the prototypes, a v8 super car, all the GT2 & GT3 cars, the shelby daytona and the 250 gto in my garage...