I didn't see why it would be an issue, I could most likely fire an uzi out of window with either hand, the other on the steering wheel...
...Unless I was at some traffic lights then I would have to either have it dropped down into first gear and would need my left hand, so the uzi would be in the right hand so I could switch into second with enough time to keep control of the car.
... Unless there was a traffic jam, not been using my hands for that and found that i can maintain a straight line with my legs. So could hold it with my right hand and steady it with my left hand, but then I could get carried away and lose control of the car, but of course my seat belt would prevent me from getting out of position too far.
Why do you ask?