http://americaonwheels.org/AOW%20Car%20Games.htm has several, most of them I've never heard of.
I have used the 'farthest state plate' to keep my mind active and looking around, and when on a long drive with someone else the name game is a fun and competitive way to see who can start the next name with the last letter of the previous full name. ie Jack Palanc
E to
Emilio Esteve
S to
Steven Spielber
G to
George Burns. This was a great way to waste a lot of time on watch while I was in the Navy too. It gets competitive when someone has to start a name with a X, Y, or V. Yasmine Bleeth was always a good bet.
Name foreign cars from a certain country was a good one too.
What did you use?
jbohjkl@yahoo.com