If you're careful you can take a couple of whacks at it with a body hammer and / or a dolly. You want to use something with a spherical hammering face and just kind of pick at it slowly and lightly starting from the middle of the dent. Seems like a lot of work IMHO, I guess it depends on how picky you want to get with the dent...

By a nice rock bumper and strike fear in tailgaters and shopping carts.

Mike