We've all seen the spike strips. But, I have thought of something that a police car could have on-board. It won't stop every car, or every truck, but it will stop the vast majority. It's a pair of hollow rubber wheels with spikes inside them. It doesn't work by punching holes in the tires, it works by punching holes in the cooling system and oil pan, and is dropped from the bumper of the police car via a solenoid release mechanism

This Forum does not allow me to edit my posts. But, I did have one other idea. It's a land mine that's designed not to destroy the car, or kill the driver. It's linked up to a radar gun in order to insure that the device explodes when the engine is directly over it. It's only powerful enough to cut a hole in the oil pan, and the detonator is calibrated to work with the radar gun so that if the engine is in the front of the car is explodes in the first 6 to 12 inches. If the car is a rear engine model, the radar gun allows the device to be triggered in the last 12 to 6 inches taking out only the engine.

I'm not so sure that you could create a landmine with that kind of precision. While it is an interesting idea, the only way that I could see it working is if the mine somehow became attached to the engine so that you could use a highly directionalized blast to put a couple holes through the cylinders. Also it would be an extremely laudible acheivement if you could link up a landmine and a radar gun to detonate within a couple hundreths of a second without spending a very significant amount of time calibrating the system before the suspect got there which just isn't feasible during a car chase.