I actually like Cars more than most other folks (For me, A Bug's Life is easily the "least" of the Pixars.).
Good characters, some solid laughs, GORGEOUS underrated animation, but a very average plot. Cars suffers from what I call the "Leap of Faith" syndrome. (Now there's a dated reference.) The trailer shows a film about racing and cool cars, but it ends up being a film about nostalgia and small town America. For me, I find the latter the more compelling story - so I had a good time with it.
But if you think about it, it's essentially the same fish out of water story as "Sweet Home Alabama", "Doc Hollywood", "Funny Farm", "Baby Boom" and the aforementioned "Leap of Faith".
Now my bias comes in where I find the idea of small-town America very appealing and tend to enjoy the "city boy gets his come upin's" trope.