There are a few things you can do to slam a car in GTA 5. The first is to use the car’s front bumper as a weapon. This will cause the car to flip over and land on its back, making it easy to take down. The second is to use the car’s side door as a weapon. This will cause the car to flip over and land on its front, making it easy to take down. The third is to use the car’s roof as a weapon. This will cause the car to flip over and land on its back, making it easy to take down.