The resume function on the cruise control sometimes exceeds the set speed and fails to upshift. An example of the scenario is the cruise set speed is 75 mph. I approach a car going 65 mph and press the cancel button which disengages the cruise control. The car pulls over and I press the resume button. The transmission will sometimes downshift to either 3rd or 4th gear and quickly accelerate to 78 mph and stay in the lower gear. I am not touching any pedals nor the gear shift which is still in the auto position. The transmission will stay in the lower gear at the higher speed indefinitely. If I press cancel and then resume it will immediately shift to 5th gear and return to the 75 mph set speed. The problem is intermittent and has happened about 10-12 times in the last year. I do use the cruise function daily on the interstate, but don't encounter the described situation very often. I have tried to reproduce the problem a few times without success. I have taken the car to the dealer but they were also unable to reproduce the problem or find any other problems with the cruise function. They also stated there was no tech bulletin describing this problem. An email to Mazda was responded to by suggesting I take the car to the dealer. I am a very experienced driver. I know with absolute certainty that I am not touching any pedals and that the gear shift is in the auto position. This is not a case of driver error. There is a clear defect in the functioning of the cruise control or transmission operation. In every other way the cruise and transmission operation has been completely normal.

- Cary, NC, USA