The recent PTR-91 post by F.B. mentioned damage to a windscreen by ejected brass. I sometimes shot both rifles and pistols from moving vehicles during training exercises. The purpose of this vehicle based shooting was primarily to teach the futility of such. What a wonderful way to ventilate an innocent tax payer. Sometimes my passenger would shoot while we were on an Emergency Vehicle Operator Course (EVOC). Driving was even more challenging when dodging hot brass. (Yes, the passenger was shooting through either side window - rifle only, not pistol for these were judged too hard to control in a moving vehicle when shooting past the driver). Most of the vehicles soon developed shot out windscreens and ventilated doorposts.

Shooting from a stationary vehicle is a horrible option tactically because the shooter is constrained within the vehicle. Although the inside of a vehicle may offer concealment, only an armored vehicle should be considered cover. Long range tactical shooting can be frustrated by rocking of the vehicle by wind (especially in Chicago and the Texas Panhandle) or even by unanticipated passenger motion.