While driving, the vehicle's changing GPS location is used to calculate speed and heading. When the vehicle goes above 10km/h, just in case the doors aren't locked, the door and trunk buttons are disabled. Popping the doors open on the highway when you're only trying to turn up the volume wouldn't be much fun. Ok, it would be a lot of fun, but it's not a great idea. "10/10 for style, but minus several million for good thinking."