It's hard to see a movie after all the hype and still have it live up to expectations. CARS does not manage to pull it off. I spent most of the first act asking "Where are the people? Who made these cars? How do they reproduce?"
Unlike TOY STORY, where the toys are real in our world but come to life, this is some bizarre parallel universe where there's a California and an I-40 and a Route 66, but no people, or other lifeforms that aren't cars.
Of course, I wouldn't have wasted a moment of time thinking about this if the movie worked. It doesn't. The two main characters are very, very weak. Lightning has literally no back-story coming in to the film. The female lead is even weaker. And the casting on both parts hurts the film. I like Owen Wilson, but not his voice, and he does not bring much to this film. Even more hurtful is Bonnie Hunt, totally miscast as a hot Porsche. Her voice is whiny and outright annoying in the film. The two-hour running time also overstays its welcome.
The minor characters all work. Paul Newman, Cheech Marin, George Carlin and Tony Shalhoub are all good in supporting, albeit simple roles.