Destroy All Humans! 2 Tips

car bombs
This is gotta be the best way to kill a lot of people quickly as possible and without the need to acquire ammo. Anything but a cop car or tank etc. will work. Simply take out your zap-o-matic and zap the car until it is under 1/4 health. (one full zap will do if your zap-o-matic is fully upgraded) then use pk to pick it up and throw it a group of enemies or another car for a chain reaction. This can be a fast, extremely effective way to take out enormous amounts of enemies.