I'm in the back seat with no air circulation, and I'll get sick almost immediately. Front seat in the same situation, and it takes several minutes. Driving, and I can go for an hour or so.

Open a window and things change. I can probably read a book in the back seat for 30 min, but if I need to change focus to horizon-book-horizon, I'll get sick faster. Same with interior-exterior-interior.. I've only ever been sick from video games once when I first played Descent, and with the invention of "Mask poor action scene with wobbly camera", I have felt a few small familiar headaches.