Roads closed due to bad weather, Gas Shortage, total power grid failure, blocked in by 4 other cars, they disabled your battery to disable your vehicleAs for the OP. If I can successfully make it to my vehicle to obtain a more lethal weapon. Why wouldn't I just drive away from the threat?
Thanks for proving my point about being so myopic that you can't even imagine a scenario a truck gun would be useful. All you can picture is walking out from your home in your driveway and never possibly needing a firearm because you have never needed one before so clearly you will never.