when I run a movie I have to find the right setting because every movie sounds different. so if the bass is up too high it drowns out everything else. so I find where it sounds perfect and leave it there. I actually go into the movie if its an action movie and set the bass to match some explosions and then watch the movie so I don't have to change it during the movie. and I guess I don't run my sub hard enough because on "bass I love you" which goes down to 10hz I believe it doesn't move that much more than at 20hz. and the way I have seen people blast their subs in their cars with huge amounts of cone movement... I never do anything close to that with my sub because I don't want to blow it. and I have a light on my amp that turns red when clipping and if that happens I turn the gain down.
Regardless of cone movement, a car is a very different environment from a room- in principal, it's similar (a speaker box firing into another space) but the dimensions and scale are far from the same. Sitting in a car, your position is similar to being in the chamber of a bandpass box between the woofer and port to the outside world and by adjusting the windows, it's tunable. Close the windows and the sound will change drastically. Opening doors and windows in a house makes similar changes happen, to a different degree.
IMO, the need to change the sound for every movie means that you need to find the best location for your speakers. Small changes often make a big difference and once you find their 'happy place', you'll be able to stop messing with the controls. For music, you'll hear large differences in sound quality, even if the speakers are in the best location because they weren't all mixed to a particular standard, like THX, Dolby surround, etc.
However, the best thing about finding the best place for your speakers- you'll find yourself just listening or watching, not thinking about it.
