oneshotonly,
The three shot (burst fire) shouldn't be needed. If you can't control the trigger well enough to only fire 2-3 rnds at a time, you need more training. The 3rnd setup was designed for the M16 rifle. It was determined that 3 was the optimum number to give the best chance of hitting a target at battle ranges. Also, they wanted to slow down the use of ammo in a firefight, as the typical soldier would empty the mag with each trigger pull (and not hit anything). However, if you have targets at your car windows, you might want to be able to throw 4-6 rnds/burst. Some of the burstfire trigger sets give a different feel each time you press the trigger, which hampers good control.
Between the two choices, my preference would be the MP-5 in any version. Very controllable, and easy/quick to get competent with. The MP-5K-PDW would be my choice. If you can only find the basic K model, the folding stock is available here. The maker of the stock is Choate Tool Corp. It is marked "HK" when they supply it to the gunmaker, and says "Choate" for the aftermarket. The K is a real handful without a stock. I'm told that to get accurate without a stock, it takes about 6000 rnds of training. The cops that use it call it a "room broom". You can flip the stock open as you pick it up, very quick. The stock locks when it hits the open position. BTW, one version of the stock locks both open and closed. You would not want that for your application as a car gun. You can also put the full stock on the K model, but it is still a little awkward inside a vehicle. You can get a shoulder holster for the K, carries extra mags on the left side, and you keep a short mag for concealment, in the gun.
If you can get the Glock G18, you might want to consider it for a couple reasons. It will fit in a regular holster, so you can comfortably carry it without any undue concealment problems. Once again, you can get a shoulder rig that carries the full size (33rnd) mags on the offside. If it is on you, it will be much quicker into action than a subgun in a rack, or under the seat, etc. If your car is rammed or crashed, you might not be able to get to the subgun, or even find it. The infamous FBI-Miami shootout in '87? illustrates why a gun in a holster is better than loose in the car. (objects in motion, etc..) The latest version of the G18 is compensated, so should be a little better handling in full auto, but might be an ear popper inside a car(you could change the barrel). The Glock is very controllable, with an educated trigger finger. Once you get beyond one or two car lengths, the nod would go to an HK with stock. The neat thing with the G18, is you can have it on you while moving to and from the car, and not look obviously armed. The HK is substantially more bulky under your jacket. Frankly, if you are not limited to one gun, I would carry the G18, and put an HK in a heavier caliber in the car for anti-vehicle/roadblock duty. Always good to have a backup gun!
Frankly, the HK and the Glock are more fun to practice with, then the Uzi's of any size. You'll get good with them quicker, and if you like shooting them, you are more likely to practice, instead of it being a chore.
Will
