Active Brake Assist

[Ron240]

To date I have owned 7 cars that have had autonomous braking systems but I have never experienced any of them working in practice...until today that is.
Mercedes system comes under the name of Active brake Assist which includes additional braking force and full on emergency braking.
I was coming home from a trip to Glasgow with my dad in the car and we were on a 50mph road when a car in front was slowing to make a tight left hand turn. I was off the gas and covering the brake just letting the car lose speed by itself and I estimated all would be fine and the car in front would have made its turn before I got too close. There was an audible warning but I took no notice because I was aware of what was in front of me and was in full control, then very quickly the car braked hard and violently and we both **** ourselves (not literally ). The braking was very brief then it released and by this time the road ahead was clear.
I was never in any danger of a collision so in this case I knew better than the car, but is clear to see the benefits of these systems and they will undoubtedly have prevented many accidents of this type.
I believe there may be something in the settings where the sensitivity of the system can be adjusted so maybe I should change it to being slightly less aggressive.

 

[rf065]

I don't believe you can change the setting, but I find it is very intrusive and it cannot tell the object in front will be clear by the time you reach the same part of the road, so brakes when not needed. If however you were not paying attention, then I can see the benefit.

 

[sonic]

I have had virtually the same happen to me, gives you quite a surprise.

 

[s5tuart]

On my CLS the system actually saved a pedestrian from serious harm. She walked out into the road from behind a parked van straight into my path.
I'd have had no chance to react but the car did!
Ron, I wonder if the sensitivity is tied in with Distronic where you set the distance to how far behind you want to travel from the vehicle you're following. Mine was always set to maximum (100 metres?) and I got very few auto braking moments.

 

[dry run]

My CLS often bleeps at me, but has only once engaged the brakes (when I was coasting up behiond somebody ast the traffic lights). I agree, the braking is pretty severe.

 

[Ron240]

Ron, I wonder if the sensitivity is tied in with Distronic

My car does not have Distronic, this only comes as part of the Driving Assistance Package which Mercedes charged £1500 for and curiously was only optional on the top Premium Plus spec.
I had a look in the settings and sure enough Active Brake Assist is there with a number of selectable options for sensitivity. It was set to 'Late' which now that I think about it I believe I selected this when familiarising myself with things after picking the car up. There is also an 'Off' option although I wonder if being a safety feature it will default back to on with the next ignition cycle like Lane Keeping Assist does.

 

[Srdl]

I occasionally get the audible warning, when I know better than the car, but never, so far, the actual braking!

 

[V6Matty]

I’ve had mine activate before, it’s nice to know it works but gosh is it violent.
I think the car thought I was trying to kill myself as I was actually accelerating for a gap on the M6 while coming up behind a waggon, the car must have thought I was going right for the back of it, just as I was about to pull into the gap. Anyway, the belts tightened, the power was killed and the car braked, all within a second, as you you have all found out, it was violent when it happened.
I do still get the beep occasionally but mostly the car doesn’t react, but it always want to start reacting on the A46 as I come up to a bridge, every time without fail, it beeps, touches the brakes and then decides all clear, how it does this on a duel carriageway with nothing around but a bridge that going overhead is beyond me to this day.

 

[00slk]

You should feel this in a 44 ton lorry when it brakes violently, for a vehicle thats already turned left or right, plus the beeps that sound out really makes you *^#% yourself.
The lorry is over protective of itself, to the stage that it'll bleep loudly for the corner chevrons.
However, in the dark of the night when a (Halfords headlight fitter) has put a new bulb in and its pointing directly at you and, I'm left driving blind, the beeps are a god send for the pedestrian or cyclist in black clothing walking or riding along the road.

 

[A.J.]

I have had virtually the same happen to me, gives you quite a surprise.

That system certainly saved me a few quid. I was coming out a side to cross the path of a stationary near side lane into the outside lane to turn right. All of a sudden a Honda Civic came out of nowhere, or at least I didn’t see him, and flashed across my nose. The active brake system reacted instantly and stopped me dead in the road. A bit startling to say the least but it certainly saved my bacon, didn’t please my wife enormously but these things happen