The thing with this one is an average driver may never know, and I may not be 100% right on this one. I took the car on a trip of about 4 hours and noticed the engine was working pretty hard to keep up highway speed. I was not sure what the engine should be running, but I had a Lincoln Mark VIII that ran 70 mph at just 2000 rpm. That was in a DOHC V8 that had a higher redline and did not have a whole lot of low down torque. This car has a relatively big V6 with just 12 valves. It has low-down torque. So when I noticed that the car was running 61 mph at 2000 rpm I thought something was wrong so I downshifted into 3rd gear and nothing happened. So as far as I could tell 3rd and 4th (overdrive) were identical. I took it to the shop and they fixed an actuator. The mechanic told me the gear shifter is not mechanically linked to anything, it is just a big switch and the part that actually engaged overdrive was broken. I had this done with about 400 miles left on an extended warranty. When I got it back, it was unchanged. The dealer told me that the part must be bad, but labor and the part was on GM now, for 12 months. I have not taken back yet, but will do so soon. Another thing I have noticed with it is that under normal acceleration it actually does shift into overdrive for about 5 mph and then shifts back down into 3rd. This occurs around 40 mph. I think this is a serious problem because #1 I am not getting the 30 mpg on the highway like I should and #2 this is unnecessary wear and tear on the engine and transmission. If anyone could reply to me and tell me what their engine is running at 60 mph, I would appreciate it.