what a great car to buid but im not to washy on the art work / flame. The render itself looks flat, needs a background / depth. The flames look harsh, sharp edges & needs a bit of transitions / blending otherwise it looks more like a sticker then paint. I would also work on tone such as the black tires & the black body have the same tone relationship, any type of metal has some transitions light / reflections. I would use gradients. A black ipod is a good example, to see the detail yoiu use blends of tone or values such as black, lighter black. Doing so will bring out the colors more so the edge of the door looks seperate & not as one piece to the car body. You cant see the door handle so work on value of blacks & see what you can do. The hood is another example, it looks like one piece to the bumber due to lack of values of black as well as the seats seem tobe darker then the body which may be due to shadows on lights then the color itself, some highlights would be nice.

As a model, the car turned out pretty good, its the texturing/lighting/renderin that needs a bit of tweaking. Good luck with this one.