Vehicle security for long road trip

4/10 shell rigged to an electronic actuator.
Load shell with saltpeter.
There are multiple locations to mount.
Simple disarm when preparing to start the car.

Peter will just take his/her eyes and won't break the windows.
Learned that from a Nam vet, that didn't usually use saltpeter.
No one mentioned this one so I thought I would just throw it in.

Booby traps