Took my HHR into my local Chevy dealer this morning and they found the problem in my wheels - it was a bad wheel bearing.
I had been wondering what it was (previous posts) and Chevy Mgr. reminded me I have a 5/100k warranty on the power train. The noise coming from my tires is gone and it's like driving a new car.
Previous to this I had also told them about my A/C not always coming on, but they couldn't find the problem. I advised them prior to the warranty expiring and today they were finally able to duplicate the problem and they're going to repair it under warranty, even though that expired 17,000 miles ago.
Finally, they replaced my bow-tie on the back under warranty.
They sure treated me right.

 

 

Glad to hear it!