The above vehicle is a 2015 ford mustang eco-boost convertible. it is equipped with adaptive cruise control. when a vehicle in front slows below a set speed or a vehicle cuts the car off the adaptive cruise control slows the car down, or stops it, to keep a predetermined distance. according to ford the slowing is done by the engine and not the brakes. once the vehicle slows, and it is safe, it begins to accelerate back to the set cruise control speed. the slowing, not being done by the braking system, does not activate the brake lights. only when the brake pedal is stepped on will the brake lights come on which also would disengage the cruise control. we have had a couple of incidents in which the vehicle behind does not see the car slowing, by brake lights, and closes at a rapid speed on the rear of the car. looking at a dodge ram closing, not knowing it's going to stop, can be a bit unnerving. i have recently read that the automatic braking may be installed on future vehicles as a standard option. i can't imagine that keeping a vehicle from crashing into a forward moving vehicle is any more or less important then being struck in the rear because brake lights don't come on. i am certainly more cautious driving the adaptive cruise control on because of this safety issue. i have talked to ford "customer relations dept" who weren't sure how to follow this up but to sent it up the ladder. i have a ford case #cas-7876013. ...updated 12/29/15 *bf according to ford, the slowing is done by the engine and not the brakes. once the vehicle slows down, and it is safe, it begins to accelerate back to the set cruise control speed. the slowing not being done by the braking system, does not activate the brake lights. only when the brake pedal i stepped on will the brake lights come on which also would disengage the cruise control. the consumer stated on several occasions, other vehicles did not observe him slowing down because the brake lights did not illuminate. updated 12/31/15. *jb