I was on a local road slowing for a stop sign, brakes and regen, when the collision warning suddenly came on. The road was going down into a small dip with the stop sign at the opposite top with a car stopped at it. There was plenty of space and I was slowing down easily quickly enough to stop very safely, actually I eased to a stop. My guess is that the front radar saw the car, but then got confused by the dip in the road and started reading the rise on the other side from where I was as the distance to the stopped car and panicked. Nothing untoward happened, but it is a situation the system didn't handle correctly.