It depends on the game engine.
You can paint some highlights to help the reflective look.
http://www.simmerspaintshop.com/foru...ts-il2-fb.html
Also I tend to give the grey a more blueish look, especially the upper surfaces.
I'd also add a little bit of noise to the gray to simulate the sprayed effect, which I think makes the difference between dope and bare metal.
The ultimate thing is when the game supports reflection maps: http://www.simmerspaintshop.com/foru...tion-maps.html