Taking another look at the rules:
"Rather than doing normal damage, these bullets do Matrix Damage. The standard ranged attack roll is made with damage increased by net hits and applied to a single device possessed, worn, carried, or implanted in the targeted individual. The device receiving the damage is selected at random by the gamemaster, or by the attacking player if they succeed in a Called Shot. Devices can only be targeted by a Called Shot if they are visible to the attacker. Damage Resistance roll is made
using the Device Rating + Firewall, along with any other damage resistance programs."
It seems you don't even have to have outside devices (like weapon mounts or changing numberplate or satellite links or weapons in gun ports or drones in drone racks, etc.) but everything carried on the target.
If you go to the trouble of taking -4 to hit, you might as well target the engine with a normal bullet - any amount of damage you do will shut down the vehicle. And considering that your matrix damage is directly proportional to the gun's normal damage, you'll probably want to use a bigger gun with correspondingly larger AP value (or just a taser)
Mind you, I'm not saying that the Zapper Rounds are bad (I gave them a +). They are just not the be-all-end-all that they might appear to be.
Also, take a look at the vehicle rules:
Steering a vehicle takes complex action - but not automatically a driving test
"CONTROL VEHICLE
This action is not really an action at all, simply the expenditure of an action to represent efforts taken for the entire Combat Turn to keep the vehicle under control. This action does not need to be taken as the driver’s first action in combat, but until this action is taken, the vehicle is considered uncontrolled at the end of the Combat Turn and may crash or be taken over by the vehicle’s onboard Piloting system." p.203 core
Noise only affects your dice pool
"To figure out how noise is affecting you, start with the noise level from real-world distance to your target and add the noise level from any other applicable situations, then subtract any noise reduction you are using. Any positive noise level you have left over is a negative dice pool modifier to your actions. Noise never applies to defense or resistance tests." p.230 core
Even more important it doesn't stop you from evading being shot at.