Looks a lot like a cross between a Ferrari, a Supra, a 350Z, and some made-up car made by someone (can't remember who, I can just remember being it attributed to the name "SuperMotoXL". not sure if that was the name of the tuning... whatever... or the game it was for, though.)
Reminds me of that Concept Mustang, and looks like that mixed with an F50.
Looks vaguely like a 3000GT, an S2000, and a Supra. This car is SWEET.
Not sure, but I see some influence from Underground bodykits (the front end).
Of course, they do look pretty original too at the same time. These are awesome. I tried to draw my own concept cars at some point, and they looked... TOO real, and also way too basic. Also, they didn't look too good proportion-wise. Because I suck at drawing, they looked all skewed and stuff.