I was driving on the highway two days ago. 55mph with active cruise control engaged. The car ahead started to slow to make a right turn and was in the bypass lane, but close enough to the travel lane that my sensors picked it up, and started the truck to decelerate. I could see it was clear to continue so I stepped on the throttle to speed up. I guess that confused things because what followed was a jaw-jarring downshift that slammed the car as though it had been struck. Hopefully nothing got damaged. In the future I will dismiss the cruise control before overriding it.