In order to use my cellphone, I have it set up to require me to unlock it with my fingerprint. You can set up multiple fingers, or multiple users, or both. I thought "if they can do this with my phone, why can't car manufacturers do it with the ignition? A driver would need both the key/keyfob and a recognized fingerprint in order to get the car to start".
Some kind of set-up like that could prevent thieves stealing cars...from dingbats who leave the keys in the cup holder...and don't lock their car doors.
Heck, those people deserve to have their cars stolen.
It would need something to test that the finger was still attached to the person. That makes the technology trickier.