BOND, JAMES BOND

This would be a question for the guys in the armor forum. There are some there that have it down pretty good.

Lots of different techniques for this but my favorite is to thin the plastic from behind. Plan where you want the holes. You want to get it as thin as possible (hold the part up to the light so you don't go too far). Then you can use a needle or other pointed tool to punch the hole. Remember to angle the impact in the way you want the shot to come from. Make sure you paint the color of the metal around the hole to show where the paint has flaked off. You can find pics on the internet and they sell bullet hole decals that people put on their real cars that look good (although why you want your real car to look like it has bullet holes in it i just don't get). If you want to make a hole in a window you drill the hole through the plastic and then use a scriber or knife to scratch in the radial cracks.
Good luck and can't wait to see the pics.

Don't forget that Bond's Aston Martin had a bullet proof shield that raised up behind the rear window. That would minimize damage to the cabin.

Chicoman -
When you're planning your "battle damage", remember that a machine gun isn't a sewing machine - it doesn't make a nice, neat line of equally spaced holes.
Have a search on the web for images of battle damage - that'll show very distinctly the irregularity of damage that's inflicted by any sort of ordinance.
Good luck!