Sadly I agree completely with this review:
Something was really missing from the film. The main meaning of the film was to step back and enjoy the journey in life. It's hard to really feel this when cars represents humans. All I could think of during the movie was "Man, they must have higher gas prices than us." and "Can you imagine how much pollution they have? An average 14 farts a day from these cars would be disasterous."
Go see the movie to support Pixar, but there is something missing, and it bugs me.