Cool idea! Seems like car thieves could probably just carry around another device to hack it, but certainly could be a deterrent. I don’t know much about it but it seems like a key is supposed to be the password for the car, so seemingly the key is where improvements could be made. Like add unique and random differences in the metal on each key and have the key slot read those and only turn on the car if it matches (…
For car keys manufacturers try to get away from physical keys for years, and for a remote keyfob it's just a cost question. Bidirectional communication allows for good cryptography with challenge-response protocol, but costs more than unidirectional. But then people want to be able to open their car when the battery of their fob is dead ...