Adaptive Cruise Control question.

[Jocko]

I have a question about ACC, not just the Jazz but ACC in general. If you accelerate to overtake then lift off does the car apply the brakes or just allow the speed to bleed off?
Why I ask this is today on the A720, I was overtaken by a Merc, and while still in lane 2 his brake lights came on despite there being nothing in front for half a mile and not being near the speed limit. I have witnessed similar brake action in similar circumstances and never gave it much thought. He carried on for a few car lengths, signalled, returned to lane 1 and continued to pull away from me gradually.

[VicW]

I have noticed quite frequently that drivers apply their brakes for no apparent reason, they are only momentary applications that hardly cause them to slow down.
The other thing about brake applications I have noticed is when in a line of traffic some drivers cannot keep a constant speed and distance from the vehicle in front without continually dabbing their brakes. I think this is because they are too close to the vehicle in front and have less margin available to adjust their speed using the throttle alone.

Vic.

[culzean]

I am sure the latest ACC can apply brakes, and assume brake lights will operate, if the brake lights do not show it would be dangerous ( and probably illegal ).

[Jocko]

I am sure the latest ACC can apply brakes, and assume brake lights will operate

That is what I thought it must be. And it was a new Mercedes so I would imaging it will have a fancy ACC.
It may depend on how much over the set point the car is travelling. Something like up to 10 mph over it allows the speed to bleed off, over that it applies the brakes.

[Kremmen]

There seems to be a recent trend for some auto drivers to perform left foot braking. This can result in frequent brake lights as they tend to rest their left foot on the pedal.

As for the accelerator brake mob, I had a journey with one some years ago and it was so frustrating and unnecessary. The funny thing was that he was always moaning that he had to have his brake pads replaced every other year.

[Jocko]

Couldn't get a definitive answer but from various posts on various forums, it would appear that yes, the car will, if fitted with the more sophisticated models of ACC, automatically apply the brakes if the speed after overtaking is considerably higher than the preset speed.

[richardfrost]

Couldn't get a definitive answer but from various posts on various forums, it would appear that yes, the car will, if fitted with the more sophisticated models of ACC, automatically apply the brakes if the speed after overtaking is considerably higher than the preset speed.

My Toyota version definitely applies the brakes as required. However the whole point, for me, of ACC is to not have to bother taking control. I very rarely accelerate past somebody when using it as it sort of defeats the object of a relaxed and fuel efficient drive.

Being a hybrid car though, on a long steep descent with a speed limit, such as the 50mph sweeping dual carriageway descent from M62 J24 towards Halifax, which has three speed cameras on it, my choices to control my speed (don’t use ACC here) is to either manually set a virtual low gear, or use the brakes. The gear option does not really cut it, so I am constantly on and off the brakes down that hill. In all my previous cars, all manual, I would have been using gears to control my speed and seeing someone like me now constantly on and off the brakes would have bugged me to the point of commenting 'do they know how to drive?'.

[culzean]

There seems to be a recent trend for some auto drivers to perform left foot braking. This can result in frequent brake lights as they tend to rest their left foot on the pedal.

As for the accelerator brake mob, I had a journey with one some years ago and it was so frustrating and unnecessary. The funny thing was that he was always moaning that he had to have his brake pads replaced every other year.

Left foot braking is pretty dangerous,  the left foot ( except for Daniel Day Lewis maybe ) is far less controllable than the right foot ( except in highly trained people like rally drivers ) and why would you left foot brake when you never want to press accelerator and brake at same time.  It you ever have to drive a manual car after depending on left foot braking it could be very problematic.  I drove autos for many years and the best place for the left foot is on the footrest provided........

[langserve]

If the ACC does apply the brakes in this situation it does so very, very gently. I was overtaking trucks on a long uphill stretch yesterday and sometimes I was a fair bit over the cruise speed. The speed appeared to just bleed off as I took my foot off the accelerator. I have never noticed braking in this situation and I would say generally the ACC doesn't have a noticeably light touch. If it feels the car in front is getting too close or a steep downhill is getting the speed up, it brakes pretty definitely.

[Jocko]

on a long uphill stretch

The Merc in question was overtaking me on a slight downhill section.