I feel like this would really be a cool feature if it was added into 4.0 as it would give players a sense of fear. Even on PVE servers. What I mean by this is that you could leave an “active” grenade in a backpack and then give it to someone, only for the backpack to go up in flames later and explode.
Another way of adding fear into players is that if your car was low on health, or had been shot a lot of times in the engine, then it would have a chance of blowing up even if it is still in the “smoking” stage. This would make players focus more on the safety of their car and not just drive through a town in their apc shooting everything that moves. Also, blowtorches shouldn’t be that overpowered in my opinion. I think that depending on the part of the car that got hit, you would have to find the part and replace it. For instance, if your door got shot, and broke off or was at a very lot health, then you could either repair it with metal sheets/scrap metal, or go find a new one and place that one on your car.