The biggest issue with deploying OC from inside a vehicle is that it tends to get back in the cabin of the vehicle too, unless you're using one of the larger canisters with spray like these and basically hanging it out the window:
https://www.copsplus.com/sabre-sabre...-16-0-oz-spray
I see Sabre has just added a 'trigger top' can to their line up:
https://www.copsplus.com/sabre-sabre...p-spray-1-6-oz - Which might work quite well in the context of a vehicle.
I've debated, repeatedly, over the potential of adding aerosol 'grenades' inside my vehicle. Having gotten stuck on the edge of a few demonstrations that could have turned riotous (or in some cases did after I managed to unass the area), the idea of being able to roll the window down, hit the lever and drop/toss the can away from my vehicle, roll the window up, and bail, it useful idea. I'm just not sure it would work in practice. Particularly with the prevalence of masks these days.
https://www.copsplus.com/sabre-sabre...grenade-5-0-oz
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Which brings us back to two issues we're seeing right now, reduced efficacy of OC due to mask wearing (aim for the forehead).
And most importantly remember this: never get out of the car
A car is the superior tool in all scenarios. Including hitting someone with it...