Until about a few months ago, our CX-9 was flawless and never had a mechanical issue. Then, it started shuddering with the sensation being similar to running over those wake-up strips on the side of a highway or interstate. Initially, I thought it was due to road imperfections. But later on, I noticed that the shuddering occurred when shifting from 4th to 5th gear, and sometimes, from 5th to 6th gear. This is also not under hard acceleration, but more like cruising acceleration. Prior to this, my dealership recommended that I do a transmission flush at around 40K to 45K, sometime around Thanksgiving 2013. I took their recommendation and had them perform the transmission flush. That's the only thing that I can attribute as having a direct correlation to the transmission issue. The technician initially stated that it might be the torque converter that would need to be replaced, but now, it seems that the entire transmission will be replaced. Luckily, this occurred before the 60K powertrain warranty expired. Otherwise, I'm sure replacing the transmission would be a pretty penny.