Sorry if this sounds daft, but can someone please advise ( when ACC is active ), if the brake lights come on when the engine slows the car down to maintain the desired gap. ??   Reason for asking is that I followed a Mondeo Vignale for 5 miles yesterday, and the brake lights were coming on in a random fashion, but appeared to be as the Mondeo edged closer to car in front.  Would hate to think brake lights are activating constantly just to maintain the gap.  Thanks.

If the car has to apply brakes to slow then the brake lights come on. If it can slow without resorting to brakes, by using gearing and engine braking, then they don't.

It all depends on how rapidly the ACC needs to reduce your speed.

Edited 5 July, 20178 yr by BillyJim