I downloaded the DLC for my PS3 (UK PSN) and at first I didn't think it worked, the cars were not in the car lot to purchase or in the garage. However, they were available online as stock cars, and the team match was there. I was thinking the worst that they were all stock, only available online and you couldn't upgrade or advance tune them.....
Anyway, 'after' racing a stock new DLC car (in the team match online) all 5 suddenly appeared in my garage, and could be tuned. So if its not working, try this.
I've since bought and tuned the Supra, its max is about 12.7 and under 500bhp so its a bit disapointing its not the extreme potential of the real cars or at least be competitive at 14, better to restrict it to 10 then. After some advanced tuning, she drifts at speed very well and its a pretty decent car to drive, still floaty, and mine still requires alot more fiddling but I'm glad its in the game. The Dodge cars and Stingray I've yet to try.
And the Team Match?..........as expected (maybe we should have the word 'death' in there!).....without penalties it's a complete punt fest with drivers ramming me, and, I wasn't expecting this but even racers on SAME side as me blocking my overtakes!!! AND racers leave the game during the race which puts the whole 'team' score out of the window with unreven sides......complete waste of time if you ask me.