The main issue with battery packs on a patrol vehicle is that they also need to be charged (down time). The issue with a generator attached to the engine is that it’s slow and isn’t a long term solution because I’d expect patrol vehicles to move to EV eventually and at least by 2040. Some kind of fuel cell system could work and be refillable quickly but also expensive. It will be far quicker for the patrol vehicle to just tow the car to the nearest 7kw or DC fast charger. Unless they run out literally in the middle of nowhere they’ll be within a few miles of another charger even today. I’d imagine most will run out either at a charger that is broken or very close to a charger/home and they just didn’t make it. Of those 3000 EV ‘breakdowns’ I’d put money most were due to punctures. None of them have spare tires these days.