> 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.
My not-even-all-that-new car just locks automatically shortly after you close the door, so there's nothing to "forget".
I have an even harder time now since one of my cars automatically locks when I walk away while the other doesn't. I've been so spoiled by that functionality.
Luckily the other car will at least notify me if I leave it unlocked and can lock it through my phone. Would be nice if it just also auto-locked.