One of my wife's clients was lucky to have the latest Passat, which prevented a creep hopping in at the LV Hospital car park.
Wouldn't be hard to rig a circuit to detect the pulses from the speedo signal and operate the central locking automatically.
Two stage unlocking is also a brilliant feature.
An override switch would be useful.
Car defense: when the unwanted approach your car doors, a steel bar whipping out from under the vehicle to take the bugger's legs out would be good.