My kids are younger (8, 6, 4, 1) but we play a lot of 'alphabet' games... either looking for the letters in order on signs or coming up with lists. We might do animals, for example, first person has to come up with an animal starting with 'a', next person has 'b' and so on. Can do this with states, cities, countries, people we know, foods (specific or broad categories), and on and on. We also go around the circle with math facts (first person 1+1, next 2+1, etc.)
I Spy books are fun for hours. Books on tape or CD's from the library so they're new.
And dollar store toys!! Who cares if they break or lose their pieces? :) They get a new one at each stop.