I had an excellent example of the ACC doing its job yesterday on a single lane road...

 

A car joined from a side road with zero notice and more than a tad naughtily, but did have his foot down.

 

I had been doing 60mph but the car rapidly decelerated me to about 40mph to match the bozo in front.

 

The car definitely didn't do a 'front assist' to slow me down, but what I am really unsure of is whether the car braked at all or used engine braking to slow me so quickly, if that is even possible.

 

Either way, what I cannot determine from the manual is whether this would be classed as a braking intervention and thus display the brake lights, or an ACC action and not display the brake lights....which runs the risk of the following vehicle meeting a rapidly decelerating car that is not telling them they are decelerating beyond the drivers own perception of speed and distance.

 

Anyone know?

Both ACC and front assist put the brake lights on if they apply the brake at all.

Great stuff, thank you.

I concur, ACC applies the brakes and the brake lights.

 

The myth that ACC only applies the rears is just that, a myth. A pity really inasmuch as a little drag on the rears would help keep the crappy cheese based discs scrubbed up.

 

In my opinion modern ACC has got shortcomings on trunk roads, not least the ones where the topography features a fairly flat terrain but with gentle rolling ups and downs, the motor is forever braking just before kicking down a couple of gears to run up the other side and of course, the vehicle following is perplexed by the continuous on / off braking / lights on what is a clear road..........

 

On the other hand, it keeps me attentive, I often will knock off the ACC whenever I anticipate an unnecessary computer controlled speed adjustment. 

 

 

My biggest issue is having to remember to disable ACC whenever I pass a cyclist (which is a lot round these parts) as these cars are (not yet) smart enough to recognise the bike 2 metres to the left for what it is (a bike) and not try to match your speed to theirs!