are brake lights on or off while ACC auto-brakes?

[candywhite12]

so i am driving at night with ACC activated. When i slow down using the button (say from 80mph to 60mph) - should the break lights be going on in order to alert the driver that's behind me?  I noticed that sometimes they do, sometimes they don't, and even when they do, it's not instant.  Same thing as when i drive with, say, 80mph and there's a big slope, the car holds onto that 80mph but break lights don't seem to be turning on. Is this how it is?

[rjwojcik]

You mean 70, right ;-)

I haven't noticed my brake lights but the car feels like it's being slowed down a lot faster than just coasting down to the new speed.  How do you know you're brake lights are coming on?

[Gulfstream11]

Its a question I've been meaning to ask for a long time. Breaking under ACC can be brutal. Obviously you can't see the brake lights
but I'm relying on the Germans to have thought of this already. Surely they come on.. Don't they?

[monsta]

They don't come on instantly, depends on how had you brake.  If you're doing a sudden slow down they come on  but for gradual stuff they seem to come on if it brakes for a certain period of time.  For short braking, no they don't come on.

[fredgroves]

At night you can see.... if its actually using the brakes, the brake lights come on... but it might be using engine braking or just backing off the throttle... it does all those things...

[candywhite12]

You mean 70, right ;-)

I haven't noticed my brake lights but the car feels like it's being slowed down a lot faster than just coasting down to the new speed.  How do you know you're brake lights are coming on?

let's say 70, sure Well at night you can actually see the brake lights reflecting on the car following. However like i said it doesn't seem to be happening always and it's worrying because if i decide to go down from, well, 70 to say, 30 and for whatever reason i have ACC do it for me, i need to know that the driver following is being notified of the sudden change.

[mcmaddy]

If people behind you don't realise the car in front is slowing then they probably shouldn't be driving. To be honest this is a bit of a non issue as if the functionality of acc was flawed then no car manufacturer would be allowed to use it. Drive your car and enjoy it and don't worry about your acc.

[candywhite12]

If people behind you don't realise the car in front is slowing then they probably shouldn't be driving. To be honest this is a bit of a non issue as if the functionality of acc was flawed then no car manufacturer would be allowed to use it. Drive your car and enjoy it and don't worry about your acc.

i disagree, it is an issue as people are often tailgating and i worry that someday they r gonna end up stuck on my boot... Not saying acc is flawed, i'm just asking whether there's something wrong with my car's system

[mcmaddy]

People will tailgate you regardless and again if they are that close then nothing will stop them bumping into you.

[Finglonga]

The Brake lights only come on when the brakes are used to slow down, just like normal driving. Engine braking would never show brake lights.