Yes, we included vehicles in our firearms training (police work) and even included high speed chases (very short) that ended up in gunplay at the stop... We also included training to recognize deliberate planned ambush scenes - how to avoid, how to retreat, and other similar tactics.. Pray, that as an ordinary citizen, you're not involved in any of that sort of action - since the good guys often don't survive it without serious harm...
What we did not train for, that I would have approved, was serious defensive use of your vehicle when confronted by an armed assailant when your life is on the line. I can understand why no police agency would allow such training - but a vehicle is a deadly weapon in its own right and prompt aggressive action can interrupt a planned attack -then allow you to retreat in that same vehicle. I suspect that serious executive protection training probably involves some of that - but not something they talk about at all...
Early on as a young cop I figured out on my own that my vehicle was also a weapon in an extreme situation - and was fully prepared to make use of it if necessary. I'm happy to report that I never got into any situations where it was used. I also figured out that I'd have a tough time explaining that sort of action after the fact... Real life is messy and seldom plays out the way you think it would so I'm very grateful it wasn't needed..