Some (Gaussian) blur in your pixelpusher app of choice will get a smooth transition from high to low. You can use the same idea to raise the Porscho logotyp on the front of the car. Bumpmapping is VERY nice in getting additional detail, without modelling it. You could use it to breathe some life in the lights/the plastic that covers them (It does not have to be a texturemap in all cases, even with procedural shaders, you could use 'wires' or 'scan lines' for the lights on this car).