Car Hood Gun?
I have the History Channel on right now and they are having some kind of "tales of the gun" episode about all different kinds of LEO weapons. One proposal was something called the electric Hood Gun in the 1950s. A gun with a funnel cone looking thing covering it mounted on the hood of the policecar that could be fired from the console or dashboard. All the driver need do is "point the car at the target and fire." Supposedly you could frive over 100 mph and shoot accurately.
Sounds like something you'd see on the Batmobile.
Was this ever actually tried out by any police departments?
Supposedly, a CHL holder could (concealed of course) mount one in his car either under the hood to shoot through the grille or covered by some kind of elaborate hood ornimant. It is a concealed weapon kept in your vehicle.
It would be kinda useless it seems to me, since it is 1) more of an offensive weapon and 2) how are you going to aim the car in a straight line and be pretty sure you're going to hit a car or person going down the freeway (yikes! which is probably why it never really went anywhere with LEOS). Now maybe mounted on the back of your car somehow would be useful if you are being chased, you could shoot .357 or 30.06 rounds into someone's engine or into the driver, but even there that bullet passes through a windshield and misses, it has to stop somewhere (double yikes)