The critic I read said it lacks "heart". Many Pixar movies have something in the storyline that tugs at your heartstrings. TS3 was a tear jerker.
That critic never had a best friend. That's all I'm going to say. Watch it and PM me if you agree that it doesn't have "heart".
Personally I am the farthest person from a Nascar type but I actually find Blue Collar Comedy guys and Mater funny. Also love the nod to James Bond - loved The Incredibles.
I did wonder how it would affect the film to have so MANY characters in it. Will be seeing it soon.
I'm not into Nascar either, but what you are seeing from the critics is pretty much base snobbery.