It has taken me most of my adult life to learn to read in a car without getting carsick. For me, the trick is to pull the brim of my hat WAAAAAYYYY down low and then turn so that I can't see anything but the book. If I can see even a reflection of movement outside the car I get sick. If I see no movement, I can read for 10 hours with no problem whatsoever.

The kindle has helped immensely with this as I don't ever have to move the book to switch pages, so I just figure out the right way to orient my head and body and just go go go!