Stop slamming my doors!

[ZsX5o3]

I stayed up late to pick up a friend from bradley airport tonight. As he's loading his stuff into my back seat I said "try not to slam the door it's actually really..*-WHAM-* All too often this is happening! Everyone I pick up is slamming my door back to the stone age. And I don't think I'm being overcritical because often when it happens the person will say "oops" or give me a scared look. This is driving me mad! The doors are exceptionally heavy, and often when I get in I put negative pressure on the door to prevent it from slamming on its own. What can I do? I often have clients in my car and it's hard to say not to slam my doors without sounding pretentious. Is anyone else having this problem? I wasn't able to find any other threads on it.