I have experienced two occasions where the engine has revved up to 3500 rpms, once I was going down a very slight decline in the road, the other time was on a flat interstate. The engine did not accelerate either time, the rpm's simply jumped for 5 - 10 seconds and then went back down. When this was brought up to the dealership I was told they were "unable to duplicate" the issue and that it was a safety feature on the car similar to jake brakes on a semi tractor. This rpm jump was a form of braking and was a safety feature. Despite my insistence that the decline I was driving on was very minimal, they continued to stick to that answer. I have not had the rpm jump since my service visit.