I was told this from the locksmith that unlocked my truck:
Have a key made that won't start the vehicle, but will unlock the doors. Put the key behind your license plate. You can't see it, trust me. This way, all you need is a penny to back the screw out of the plate and you have a way to get into your car, but you can't start it. Just make sure your keys are actually in there or you won't be able to disable the alarm. Always put the key back when you remove it.
It's worked for me.
Fine if you left your keys in your vehicle, but what happens when you take your keys with you and lose them?
