Can you shoot while driving?
Solution 1:
You can not shoot whilst driving in Watch underscore Dogs.
Solution 2:
No you can't, according to these sources:
vg24/7 Review
Q) From T-Dawg6: How is driving in the game? I heard its a bit stiff. Also can you shoot while driving? & can you fly airplanes/helicopters?
A) You heard correct T-Dawg. Some of the cars are really sticky on the road, so you won’t be pulling off Ridge Racer-grade drifts or anything like that. I would have liked it to have been a little slicker, but you get used to it over time. You can’t shoot while driving either, and I suspect that’s to make you use hacks while driving to give cops the slip instead.
There is also a discussion at GameFAQS
Solution 3:
No, as far as I know, you can not shoot while driving. In a tutorial text in the beginning of the game, it is explained that the advantage of a co-driver is that they can shoot, while the driver can not. You will also notice that enemies won't shoot either, unless they have a co-driver.