Adaptive cruise control

[DoodleDids]

Just wondered,

When using the adaptive cruise control any idea (if at all) how much the brake lights come on?

There are roughly two scenarios - you are going along and slowly catch up with something in front and the ACC just "powers back" - No brake lights?

Someone pulls out in front of you, the ACC slows you down rapidly - Brakes with Lights ? and throttle release.

Asking as you see lots of people seeming constantly on their brakes and wondered if this could be due to their cruise control.

 

[StylancePaul]

To be honest I'm not sure, in scenarios where the car is braking semi rapidly I'm usually looking forwards not stood at the back of the car.

In some seriousnes, any application of the brakes should trigger the brake lights, and I don't feel many times the car just easing off when approaching a car in front.

 

[Dt-spd]

It all depends on the rate of deceleration, if the ACC is braking over a certain decel rate then the brake lights come on.

 

[GTI-Pirelli]

A lot more than you'd like to think they do!

Scenario 1 - Brakes + Lights
Scenario 2 - Brakes + Lights

It will not apply the brakes without the brake lights. By law it can't. AFAIK the only time the brakes are applied without the lights is a brake disk drying feature (Not sure that the Leon has this). Spoke to a few people working on ACC @ JLR.

I was curious about this when I got the car. I did a little bit of experimenting.
- Set the cruise to the speed limit and let it settle. Lower the controlled speed by 5 mph. It seemed to coast. With a 10 - 15 mph reduction in speed, it brakes.
- When following someone it seems to be constantly on the brakes to maintain the optimum distance. This is due to the fact that it will not use full braking force to slow the car so has to apply them early to avoid it. The system won't carry out a braking maneuver that could cause the person behind to hit you. It is to avoid the fine line between a driver assistance system and full autonomy. The law is still fuzzy where it comes to full autonomy (i.e. who's fault a crash is) so the driver is still fully in control.

If you are on a pitch black road, you can see the reflection of the brake lights on furniture, trees, bushes etc...