Weapon that can stop a vehicle born IED

BBC:

A British company has demonstrated a prototype device capable of stopping cars and other vehicles using a blast of electromagnetic waves.

The RF Safe-Stop uses radio frequency pulses to "confuse" a vehicle's electronic systems, cutting its engine.

E2V is one of several companies trying to bring such a product to market.

It said it believed the primary use would be as a non-lethal weapon for the military to defend sensitive locations from vehicles refusing to stop.

There has also been police interest.
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"The RF [radio frequency] is pulsed from the unit just as it would be in radar, it couples into the wiring in the car and that disrupts and confuses the electronics in the car causing the engine to stall."

He did not provide other specifics. However, the Engineer magazine has reported the device uses L- and S-band radio frequencies, and works at a range of up to 50m (164ft).

Some experts the BBC has spoken with suggested that turning off the engine in this manner would not stop vehicles rapidly enough. Others worried about what effect it might have on a car's electronic brake and steering systems.
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I think the concept has some potential especially against a determined attacker willing to crash into perimeter defenses.  The military should definitely have an interest.