A senior officer (22+ years) told me this tip:
If you are transporting someone, taking someone to jail, or even just patrolling, try to drive in the lefthand lane whenever possible. If someone is going to try and ambush you by pulling up alongside and shooting at you, then you will have more vehicle between you and the shooter to absorb bullets.
The other advantage is that if the ambush vehicle is in the right lane, the attacking driver’s shooting ability can be impaired by your driving and weaving into his car, requiring him to focus on driving more than shooting. This leaves only the driver’s side rear for a shooter who doesn’t need to watch the road. If it is reversed and you are in the right lane, the attacking vehicle can have two shooters (front and back seat) who can focus on shooting instead of the road.