lordbrockington: I mean, look at the Grand Theft Auto series. It's often totally obvious what real-world cars inspired the in-game models. They just give it a slightly different body shape and a goofy name to avoid paying automakers. I certainly don't lament the fact that they aren't "official".
You might not, I might not, but I imagine that for a lot of the die-hard enthusiasts, one of the major selling points -is- the authenticity. These aren't quite hardcore sims, but they're still not arcade racers, either, and for the folks who are really into the auto scene, you'd figure that this is the closest they're going to be able to get to owning/driving that classic muscle car, or that multimillion dollar supercar.
Hell, I just picked up a copy of Grid like a week and a half ago, and while I'm not a big car guy, either, I'll admit that the attention to detail, making all the cars "look" right makes the game feel a lot more real, even if I know it's not.