I've been hit by the door corner when somebody went to slam the door shut and I was too close.
@ crystal: is your E70 auto closing ? I think that may not open quite as high, other thought: color based; what color is E70 v E53.
You could use my tip above to add a rubber bumper on the corners, I'm going to do it to mine I'll upload pictures of course.
Back to the color: add some warning tape to the inside edge of the door, I'll be doing that as well.
Something like this stuff. Look at the inside edge of the doors how they have red tape to make them visible.
Make it Bright contrast so you will see in your peripheral vision.
One last thought: you can use some glow in the dark tape for at night but not sure how it would get charged. I think the danger tape would nearly eliminate hard banging.
@OP: thanks for bringing up this painful subject, I'm going to do the mods I mentioned and It will help reduce how often I bang my crainium (and reduce the pain when I do.