I gotta say, I love the look of the cars, and the sound at idle. When it starts revving up, it sounds odd, but since I don't know how much work actually goes into just making the exhaust note, I won't rate you too hard on that. My only real complaint is that they all just launch so darn slow if you rev it up in neutral and slam it into first, even with traction off.
Other than that, the cars are fast as hell, and again, I love the looks of it. Great work, I hope to see future updates :D