> as for "I often forget to lock the doors"... why do you often forget to lock the doors?

Having just switched from an "old-school" car to one of these "keyless" types, I think the problem is actually self-reinforcing -- the keyless entry and start stuff means you interact with the key less and less so you're more likely to forget to interact with it to lock the car. I can't think of a time I forgot to lock my old school car and yet it's happened more than once with the newer car since I got it a few months ago.