I watched this movie with my 10 and 13 year old grandsons. We watched in 3D. The movie isn't about a plot so much as the action it involves. A character, Sir Miles Axelrod has invented a new fuel that doesn't deplete the planet's shrinking oil reserves and wants to prove it in a World Grand Prix to be run in England, Japan and Italy. This is very cool. It is a masterful way of introducing new backdrops into the races, and the movie is so visually complex that I imagine details were slipped in just for fun.
Anyway, "Cars 2" was fun. Go see it. We had a blast!