ACC turns on the brake lights if it's deceleration exceeds 0.1g. that's the design spec and what it's supposed to do, at least.I have a couple of beefs with ACC. First, I dislike the sudden and rapid slowdown if a vehicle enters the zone. It's not gradual as it is if I were braking and it feels like I have no control. Secondly, what about the cars behind me? Do my brake lights come on, or am I suddenly throwing a big slowdown surprise with no warning?
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