2014 BMW i3: Adaptive, Over-Reactive Cruise Control
by Mike Schmidt, Vehicle Testing Manager on November 4, 2015
This morning I drove our 2014 BMW i3 into the office. It was just after 4 a.m. so I practically had the freeway to myself. Being an electric vehicle, our i3 has carpool lane access stickers, so I was driving in that far-left lane on principle. In peace.
Actually, the car was doing most of the work. I had the adaptive cruise control system engaged so even if a slower vehicle pulled ahead of me, the BMW would slow to match its pace. But as I soon learned, the adaptive cruise on this i3 stinks.
There I was, no motorists within 10 car lengths of me in any direction and in this quiet moment, the i3 decided to apply the brakes. Maybe it just cut the throttle. Either way, the event was abrupt enough to cause me to sway forward in the seat and put a little scare in me. A quick scan of my surroundings put me at ease. There was no imminent danger. Why the heck did that happen?
Lucky me, I had several opportunities to figure it out. The problem repeated itself five times during my 40-mile drive. Each time, I was in the carpool lane. It happened three times when the road was curving right (away from the wall) and twice while traveling straight. Did it pick up the headlights from a passing car? Was it a shadow from an overpass?
I tried recreating several scenarios but could not get the cruise to fail on command. It was set on the shortest following distance, about 4-5 car lengths. Under normal circumstances, the system detects a car roughly 10 car lengths away and gives a visual cue on the instrument panel. On the surface, adaptive cruise appeared to be working as designed. But clearly it was not. I could not figure it out. All I really learned from the experience is that I won't be using adaptive cruise in that car again.
Mike Schmidt, Vehicle Testing Manager