Someone above (I think it was Larry Gude) asked about GPS tracking systems on trucks.
I know that OnStar is now introducing an engine cut-off system to foil car thieves. That originally didn't sound like too good of an idea to me, because when the motor is killed, so is the power steering, and one only has one more shot at the power brakes. I would rather see a car thief get away than see him skid into a minivan full of a loving family.
For the trucks, however, there could be a variety of methods. The best would probably be a hidden Bluetooth transmitter somewhere on the driver's person. Once the Bluetooth link is lost, the truck fires irreversible charges that closes the fuel line and opens the air lines, engaging the brakes.