I have my dynaudio on Dynamic and I don't think I have adjusted the equalizer (would have to double check). Sounds great to me, no distortion or rattles at loud settings (50%+). I like some bass heavy music too - was playing Moderat's first album (self titled - Moderat) at 50% ish yesterday and sounded awesome!
Not sure what would explain your car Mr Savage, other than being able to compare with someone else? Maybe the default is not actually the default (like it's calibrated incorrectly or such like.)
I make sure I don't have any lose items in the doors and also that the rear cubby holes are padded with shopping bags if I have stuff in there - anything lose does like to vibrate.
