Can't be of much help, sorry.

The problem with an electric parking brake is that you can't 'feel' how much pressure has been applied to the rear discs, with a conventinal system you have a certain amounts of feel.

Car was fully loaded when you stopped, chances are the rear discs were as hot as they were ever likely to get, if they contracted as they cooled then enough pressure could have been released to let go, not saying this is what has happened.

Another possibility is that scourge of modern cars without proper torque converter auto boxes (which often have to be left in P, transmission locked, to get the key out), hill holds that apply the brakes, did the parking brake really apply or was the car left on HH only..this is a problem with some lorries by the way, and they should not be fitted with a hill hold device at all..driver controls lorry not the other way round.

By rights you should always leave a car in gear in case the parking brake fails, especially if theres danger of runaway rare with normal parking brakes as that is, its still good practice, its not always easy as some semi auto type of boxes don't have a 'Park' locking device, and putting the car deliberately into gear before turning the engine off isn't natural you're tricking the system....also the steered wheels should be facing into a kerb or similar where possible on a hill.

What does your handbook advise about the parking brake/leaving in gear...that might be an avenue to pursue.

Yours isn't the first VW to disappear after the vehicle was parked, been a good number of cases reported on various forums, usually Passats, a trawl of VW forums could be worth some time.

Edited by gordonbennet on 02/06/2014 at 08:48