Here is an interview with Paul ANderson where he hints at the fact he may or may not be off the film...

From Latino Review...

Latino Review: Does [Death Race, your upcoming movie with cars locked in a heated death race] prepare you to do another [car film] like Spy Hunter?

Anderson: I had some what fun making this movie and I firmly believe this is the best, most spectacular car action I've ever seen in a film, I don’t know if I’ll ever do another car movie after this, because I really feel like we pushed it to the max and the only other car movie I’ll do is maybe a sequel to this, knock on wood, if this movie does well enough to deserve that, I really think we’ve kind of raised the bar when it comes to car action….we’ve done everything practical, we’ve done spectacular stunts, we’ve kept it R rated, really hard, we’ve had the actors do a lot of their own driving, so you know, I think we’ve really maxed our car movie, so I think we’ve laid down a challenge to any one else, I think we’re now the movie to beat.

I take it he's never heardof a film called Bullitt then....