In the Christopher Nolan Batman trilogy, the Batmobile has the driver's seat change between driving and attack modes. Is there an explanation for this? It seems like the "attack" mode would be hard on the back, and make it easier for you to hurt yourself when moving violently.
In "Attack" mode, the driver's seat moves to the center of the car, and the driver is repositioned to lie face-down with his head in the center section between the front wheels. This serves two main purposes: first, it provides more substantial protection with the driver shielded by multiple layers of armor plating. Second, the prone position reduces the risk of injury a driver faces when making extreme driving maneuvers.
Whether this has any basis in fact is unclear to me, this reads to me like something from some publicity material put out to accompany the movies...
I can't think of a medical or technical reason. The human body isn't really designed to take much stress along it's major axis. If you squeeze the backbone and neck too much, vertebrae can become dislodged or the intervertebral disc can be damaged. This can lead to paralysis, possibly permanent or severe pain (like lumbago).
If the stress is along the minor axis (say pressure against your back) and you're lying against a flat surface, the body can cope with that pretty well (until your internal skins start to rip).
From a technical point of view, your stance doesn't matter to the button which ignites the jump drive. It's even a silly idea because the additional mechanic will make the whole machine more heavy (= less jump distance) and much more brittle.
If the technology of the world was much more advanced, I'd argue it didn't matter because materials and technology give a designer so much leeway that they could just add it on a whim, i.e. for no other reason that they can and thought it "cool". But the world in the movie isn't that advanced.
From a visual/movie making perspective, it makes perfect sense because it gives the batmobile that certain "awesomeness" which it deserves.
It's just a cool thing to throw into the movies. Having a machine cram your head down between your ankles would not serve any purpose whatsoever (it never shows how his legs go from the pedals to behind him during the transformation). The only other alternative is that his legs are behind him at all times, and his spine has been liquefied to allow his back to bend greater than 90 degrees so he can appear to be seated in the vehicle as normal.