Driving in heavy traffic in the rain at 5 to 10 mph with the ACC maintaining speed. Follow-distance set to max because of wet conditions. ACC speed set to 40. With about three car lengths in front of me, Clarity suddenly accelerates hard, apparently determined to reach set speed despite lead car going at a crawl. I brake manually to avoid collision; don’t know what the car would have done on its own but unwilling to find out. This happens three times, so It wasn’t an anomaly. Has anyone else seen this behavior?