The proportions of the car indeed look better on the first one, on the second pic it looks awfully stretched. In addition to the dirtiness the biggest problem is that the car's perspective is wrong. It looks as it is being viewed from a different angle.
Made a very quick edit to show what the car's perspective should be like. (I know it's not perfectly right but it should give a clue)
Made a very quick edit to show what the car's perspective should be like. (I know it's not perfectly right but it should give a clue)
