Do you mean that the reflections are not convincing enough? I did find it difficult to create an atmosphere, and then create the car from a reference in an entirely different atmosphere, and try to make the reflections and coloration more of a match for the scene. I guess I can't really aim for photorealism if my references aren't good enough... Even if its not totally photorealistic, I am happy with it..
the Mustang Giugiaro was a prototype mustang that if put on production would sell at a minimum of 80,000. most mustangs new range of 20-25 and the Shelby at 65. Compared to a lot of other cars they aren't expensive. Unfortunetly in comparison to what most people can afford it is, at least...the one in the picture is.