Originally Posted by velociabstract
If I'm not mistaken, and being a new owner it's a possibility, when you unlock the doors the hatch and gas door unlock. When the doors lock for what ever reason, the hatch and gas door also lock. So if you can't get the door open be sure both doors are unlocked. Unlocking just the drivers door won't unlock the hatch and gas door. If I'm wrong someone more experienced will correct me.
Les
The key fob can be set to unlock all the locks with one push of the button or only the drivers door. In the second case the fob button needs to be pressed twice to unlock the remaining locks.
When all of the locks are unlocked, and the hatchback or a door is not opened, the locks will relock after a minute or so. If a door or the hatchback is opened, then the locks remain unlocked even if everything gets shut again. So when buying gas, I lock my car up before going inside to pay. When I come out I hit the unlock button so I can open my gas door. By the time I'm done pumping gas the locks have relocked and I have to hit the unlock button again in order to close the gas door. Not sure why Mercedes does this.