I agree with you. I don't see the humour in any of those other films you mentioned.
I just love everything about Cars, it has a really good story, I love the "moral" of the story, how he used to be a selfish racing car, who only cared about being famous and winning the piston cup...... but then changes and gives up the cup to help a struggling old car past the line before him... awe!.
Why doesn't everyone like it?????