I think 1:1 would be fine. You dont have to turn your head a full 90 degrees to see beside your car, you only need to turn your head far enough to where what your looking for is just in view on the edge of the screen.
If your looking foward you still get close to 45 degrees of vision on either side if your on a widescreen TV, so you would only have to turn you head 45 degrees to get the side of the car on the edge of the screen.
I also think every slight head movement should be registered onto the screen. Imagine the head shaking a rally car driver goes through and the g forces put on a F1 driver. I think I can handle keeping my head straight on a sofa. To me, its just good driving practice to not try and steer the car with your whole body. I sometimes put my hips into a turn but to drop a shoulder a lean into it seems like something a dude in a lo rider would do. Which makes me think, I find it annoying seeing guys drive while practically laying on the center console. How is that even comfortable?
Again, you have to try it to see... I totally get what you are saying, and up until I tried it myself, I would have been agreeing and saying the same thing with you.
First off, turning your head, while what you are saying makes sense, it doesn't work in practice. The turning ratio HAS to be increased to make it feasible and the real problem is that while turning your head is natural to look into the apex of a turn, looking out of the very corner of your eye to see the view you should see while looking directly ahead of your face isn't intuitive.
As for holding your head straight, it's not the nead to be perfectly still or straight all the time that is the issue, sure real race drivers experience massive shaking of the head, but the problem is that the direction you see onscreen is relative to your head and so it is often that what looks like straight ahead is actually a few degrees off to the side causing you to feel like your car is drifiting when in reality your point of view is just off a little.
This was an issue with Wii one of the wii FPS, your aim went where the wiimote pointed. Seems straightforward and awesome right? I mean when you really hold a gun, you really hold it pointing forward most of the time no matter what right?
In practice no... it was very unpleasant, your arm and wrist got tired holding the wiimote in place to keep the camera from having the shakes.
Again, this is something you have to try to understand. It's all fine and good to talk about how these issues won't be a problem, but when you really try it, you suddenly see just how unnatural this all is. The whole idea of looking right to change your view, but then having to look out the left side of your eyes at the TV, which never moved relative to your body but just changed pov... I think it's just not a good way to do things.
There is free software to do this on the PC (and while I can't think of the name now, a few years ago I had a free one that did face tracking so no lights needed) so you could try it if you want, but an easy way to fake it is this:
Get a game loaded that supports the right analog stick changing your view to look around.
Have a friend control the right analog stick while watching your head. Drive down a road and have your friend try to match your head movement to the stick to change your pov in the game.
This won't be perfect of course and it depends on your friend doing it right but I think you will quickly see just how unnatural it feels.
Or you can try to do it yourself if you are good at controlling a lot at once, use the right stick to change your view while moving your head around. Again try to match the stick to your head movement.
As for holding your head steady, put a bright light behind yoru head so it casts a shadow of your head on the wall in front of you. Line your head up so it's shadow just touches some stationary objects (like a bookecase or edge of a window etc), now play a game while holding your head so the shadow never moves from these positions.
I gaurantee you about 5 minutes into it you will be thinking you have head your head perfectly still for hours.
The reason it needs to be perfectly still and not just mostly still? Constant little jiggles on the screen from a moving head really get annoying quickly, and no it's not at all like experiencing a bumpy road while riding in a car, hard to explain but it's just not. This and the fact that I talked about above whereby if your head moves a few inches either way, it can throw off your view so what looks straight ahead isn't, however it won't be enough to easily notice on screen so you will be constantly feeling slightly off center.
We can talk about it all you want and how you are sure these issues won't really be issues... but I have done it... they are issues. I am just telling you how it works. Watch the video of the guy playing grid in the news section... you will notice the only times he uses the head tracking to change his view is when he is sitting still, or when he is burning out just to kind of show it off. During all his actual driving... nothing... why? Becuase it's actually a dissorienting thing to use while trying to control a car.
And before anyone says "it's not released yet, you don't know how Sony will do it" we have seen the video of how it works, it's exactly how my head tracking software worked. And there are only so many ways it can work, again it's the fundamentals of how it works at questino here, not the details.