Comment This is a known issue (Score 5, Informative) 424
Tesla Model S uses a proximity sensor to detect the key fob in your pocket and extend the door handle with a motor:
To quote from an article:
"From the instant you walk up to the Tesla S and the door handles motor out of the door, you know this isn't going to be like any other car you've ever driven. You open the door and the air conditioner has fired up, and your music is already playing. You put your foot on the brake, shift into gear, and you are off and running. There is no âoestartâ button. When you arrive, you just get out of the car; it turns itself off and locks up as you leave."
Tesla originally had a sleep mode for the inboard computer that was supposed to consume around 1%/day. But they found that the sleep mode often resulted in the car not detecting the key fob. So they disabled it until they could patch it. Not surprisingly, it sucks a lot of power while its sitting in non-sleep mode waiting for someone to walk by with the right key fob. If they had stuck with a manual door handle and a push start button for the engine, then the idle power issue would never have come up. In any case, Tesla is working on it and will resolved it eventually.