My answer assumes, that you already tried simply talking to them and it did not work and also, that you DO want them to exit the vehicle at exact this place.
Since this is Lifehacks, not "How can I train my passengers to behave like I want", I would recommend taking steps that, even in the case of them smashing the door against the wall, the damage will be intercepted or minimal.
You could install some kind of buffer, either at the wall or your door.
A buffer on the car might make your car look ugly though, so this may be an issue for you.
But the big pro is: it not only works in your garage, but in every public parking lot as well. Also, it's cheap (maybe $5-10).
The con of this is that the buffer will absorb the damage for you and in doing so, it will wear off within some hundred usages.
The alternative is a rubber buffer on the garage wall; a far more durable solution and it won't make your car ugly.
A rubber impact bar can be bought in any hardware store for as cheap as the other solution. Compared to the car-bar, this solution is of high durability.