I don't know if you use your car for driving to work and back home, or going camping, or.. if you are a driver, like long distance driving. If you are, you must know about travel pillows.
I see a dozen of manufacturers, all bragging about how warm and fuzzy and neck tension releasing their pillows are. And i believe them. Occasionally i drive for 3, 4 hours and my neck hurts, and my ass also :) Most new cars have already implemented this kind of car gadget, hours and hours of testing really paid off in some cases.
Bon voyage !