yeh the DLC cars are just like any other in your garage, usable on any race on or offline. I bought them as like many other GT5 users, i enjoy the car collecting side of it so i couldnt not buy them. i especially like the R32, 33, 34 and 35 skylines, probably cos ive always loved these cars regardless of spec. But one thing that was kinda quirky was that i wanted to really tune the R32 racecar and make it a bit more of a beast, so i did, bigger turbo etc, painted it black with the black wheels to make it look a bit more aggressive, and after a few laps of Spa in it, the power was exactly 666bhp lol