moveover

Thinking of upgrading the security on my WRX and one of my friends mentioned an immobilser that has a tag you can wear round your neck, in pocket etc. It needs to be within a certain distance from your car to start/run. If your car is running and the tag is not in range( Car Jacked??) the car cuts out.

Thinking more discrete than the keypad idea.

Had a search about can't find anything about it. Anyone any ideas.