I like the idea of not having to carry keys, but having designed with fingerprint readers, I don't trust the .jpg ones--they were easily fooled (with a photo of a finger for instance) when I was using them, where the sound-wave ones are bulky and expensive.

It's been two or three years since I designed one, so maybe they're better now...

Also, this would require some kind of 'system manager' function like passwords on a computer--and would your approved fingerprints be stored in permanent memory? If you sell it, that means you need a 'reset' button to make it forget the originals--but what if your three-year-old presses the 'reset'? Also, when a car is being loaned or driven by salesmen for test-drives, this becomes a difficulty--they'd all have to be registered.

Almost seems it would be better to use a secret number-code. But people can forget these...Maybe the best way is a key.

You could design it to use either a finger print or a key. That way, if someone borrows the car you can just give them a key. The finger print reader would just be available for when you don't want to use a key.

Hrench, I sure that resetting would require more than just pressing a button. It would no doubt require a procedure that includes punching in a secret code number or something along those lines.