I found that my vehicle was running really rough, at idle and driving, and I had noticed that my gas mileage had dropped significantly. I took it into the Chevrolet dealership to have a diagnostic run. They found that my injectors were bad. They said they needed the car until the following day. No problem. Then they called me and told me that they found I also had a burnt valve. They had to keep the car for a week. Fortunately, it was covered under the GM 5year 100K warranty. I was really close to 5 years. If this would have happened later, I would have been screwed. I was happy that it was taken care of and so far, I have not had anymore problems, but it has only been a couple of months since the repairs were done. This frustrated me because of the other problems that I keep having with this car. Mainly, the brakes. I will buy another Chevorlet tho. I have a 2003 Cavalier that I bought brand new and have never had an issue with. Chevy will get one more chance from me. I will be getting rid of the HHR as soon as I can and I wont buy another one. Kinda sad because I do like this car. It is great for road trips. I just cant handle doing my brakes every few months.