I have to agree with Mr. Commie here. Cars is a really good movie. I suspect few adults without young children have bothered to see it figuring it’s just another kid’s flick. I probably wouldn't have bothered to see it if not for my pre-schooler. Because of him though, I’ve seen Cars, in whole or in part, dozens of times. Sure kids like it, but it has a simple yet compelling story that’s enjoyable for all ages. There are plenty of references to things only adults would understand. And, as A/C points out in his post, the animation from Pixar is truly amazing. It’s worth watching for that alone.
I also like the cast of voices. From Owen Wilson’s Lightning McQueen to Larry the Cable Guy’s Mater to Bob Costas’s Bob Cutlass, the casting is great. Cars also may well turn out to be Paul Newman’s last movie gig. So even if you don’t have kids around, check it out sometime. Or have your neice or nephew over and watch it with them.