Hey,
I see that it's a qouick chop, but it is full of mistakes. The BG is off first of all. The paintjob and the color of the car is terrible, it's not realistic at all... if you use photoshop than use ctrl+u combination, choose the color u'd like on the car (make sure it's a realistic color like green, blue, red etc, not liek that greenish gold stuff...) than use ctrl+b to balance the color (only if it's needed). I dont really know what that green spot on the floor is, but if neon, than search for a proper neon tutorial and do it again with the help of the tutorial step by step. ))