[Lux700]

With the ACC you get the collision warning and, if ignored, braking intervention; has anyone experienced this? I sometimes feel the urge to see if it works, but bottle it when I get as close as I feel that I should be putting the brakes on, so always beat the system!

[SilverFox335D]

Yes it works! I have found it will action the warning symbol and vibration if I predict a car in front turning and that at my rate of approach it will have gone before I arrive-if that makes sense.
It will also come on if I move across from one lane behind a vehicle and then into the outer lane a little closer than it feels safe.
All in all a sound back up. I am alert to my actions but a reminder is never amiss.
Not tried it in a real emergency scenario however! Thankfully!

[sahajesh]

Not tried for real but there are a few scenarios where it thinks you may hit something and it trigger/brakes when you wouldn't have done so.

If there was someone else right on your tail, they may rear-end you (their fault) but still..

I'd choose it again though, useful for motorways etc. Scenario above is with ACC installed but not active i.e. town driving.

[....,,,,..,,..]

Originally Posted by sahajesh

Not tried for real but there are a few scenarios where it thinks you may hit something and it trigger/brakes when you wouldn't have done so.

If there was someone else right on your tail, they may rear-end you (their fault) but still..

I'd choose it again though, useful for motorways etc. Scenario above is with ACC installed but not active i.e. town driving.

Systems like Ford's active City Stop are active during town and city driving, it's active from around 18 mph.

It apparrently breaks very hard without warning if driver has failed to take action, designed that way.

So don't tailgate new fiestas driven by grannies

[FSE23]

I don't know if it automatically hits brakes but at a few occasions i got red car flashing and bip just tenths of a second quicker then my reaction. I assume it recognizes the speed diference very well and if it is too high it triggers the alarm. That happened when motorway traffic stopped all of a sudden.

[SkyJawa]

Originally Posted by sahajesh

Not tried for real but there are a few scenarios where it thinks you may hit something and it trigger/brakes when you wouldn't have done so.

If there was someone else right on your tail, they may rear-end you (their fault) but still..

I'd choose it again though, useful for motorways etc. Scenario above is with ACC installed but not active i.e. town driving.

Originally Posted by SilverFox335D

Yes it works! I have found it will action the warning symbol and vibration if I predict a car in front turning and that at my rate of approach it will have gone before I arrive-if that makes sense.
It will also come on if I move across from one lane behind a vehicle and then into the outer lane a little closer than it feels safe.
All in all a sound back up. I am alert to my actions but a reminder is never amiss.
Not tried it in a real emergency scenario however! Thankfully!

Both of the above! I've had it happen when a car was pulling off a sliproad and I was gaining on it, I know I'm not hitting it but the car doesn't!

And a few other times it triggers when it thinks you aren't going to brake but actually you are going to!

On the whole I'd say its about 95% good to have on, with the 5% of times it getting it wrong not being enough to turn it off.

[NISFAN]

Mine was triggered by one of those foil crisp packets. Quite amusing.

[SkyJawa]

Originally Posted by NISFAN

Mine was triggered by one of those foil crisp packets. Quite amusing.

In a faceplant against the windscreen kind of way

[NISFAN]

Originally Posted by SkyJawa

In a faceplant against the windscreen kind of way

Not quite, it was being blown across the motorway, so was only a 'target' for a split second, but out of the blue I had the RED car flash up and the br,br,br,eeeeeee alarm with some braking but not emergency brake force type braking.

[sahajesh]

I tend to use it on motorways in UK and abroad, useful do maintaining a max speed but fluctuate up to that - if the car in front brakes heavily, your car does, engine stops and restarts as well.

[Lux700]

Sorry, I should've said... I meant just when city/town driving, when the ACC is not engaged but still get the collision warning and brake intervention. I've seen the RED car pop up on the HUD and heard the beeping, but it's always when I've been negotiating traffic and trying to make progress, so I've always been about to brake anyway; it's just that system seems to cleverly calculate (as Piono and others have stated) the closing speed, and put up the warning. I was just wondering, would it actually stop the car if I chose to ignore the warning? Anyone brave enough to test it, or does anyone have knowledge of what would happen?

[SkyJawa]

Originally Posted by Lux700

I was just wondering, would it actually stop the car if I chose to ignore the warning? Anyone brave enough to test it, or does anyone have knowledge of what would happen?

No it doesn't do this. It just pre-brakes for you and stiffens the pedal so that you have max brake force to apply when you stamp on them. The warning and beeps is to tell you to wallop the brake pedal down. The idea being that because its already started braking for you the impact speed will be less than if it was just you doing it on your own.

[Daftasabrush]

Originally Posted by SkyJawa

No it doesn't do this. It just pre-brakes for you and stiffens the pedal so that you have max brake force to apply when you stamp on them. The warning and beeps is to tell you to wallop the brake pedal down. The idea being that because its already started braking for you the impact speed will be less than if it was just you doing it on your own.

I have experienced mine actually applying the brakes, so it definitely does more than pre-brake.

[SkyJawa]

That's what pre braking is, its starts to apply the brakes for you for you to take over, but it potentially won't stop you. Hence the audio warning telling you to brake harder

[Beancounter_74]

ACC is billed as coming with 'stop/go' though, that implies it will come to a complete halt.

I'm sure no one expects it to assume full control, but in a controlled manor in normal traffic I was expecting it to bring the car to a standstill then pull away again once clear to do so. :

[SkyJawa]

Make your own mind up, there doesn't appear anything conclusive, and I'm not testing it for you

http://www.bimmerpost.com/goodiesfor...e_Systems1.pdf

http://f30.bimmerpost.com/forums/sho...d.php?t=688217

http://www.bimmerfest.com/forums/sho....php?p=7431815

[johno]

Originally Posted by Beancounter_74

ACC is billed as coming with 'stop/go' though, that implies it will come to a complete halt.

I'm sure no one expects it to assume full control, but in a controlled manor in normal traffic I was expecting it to bring the car to a standstill then pull away again once clear to do so. :

Just to clarify for you: If you spec ACC you get collision avoidance "for free", and collision avoidance is active even when ACC is not active. It's collision avoidance without ACC active that the OP is talking about.

ACC, when active, will indeed bring the car to a complete standstill, and turn off the engine. It will start the engine when the car in front moves, but won't actually move off until you either tap the resume button or press the accelerator.

And, like others, I've experienced the red light and some pre-braking, usually when I know the car in front is turning. But I've never had the nerve to see if it will actually brake sufficiently to stop me from rear-ending someone.

[Beancounter_74]

Originally Posted by johno

Just to clarify for you: If you spec ACC you get collision avoidance "for free", and collision avoidance is active even when ACC is not active. It's collision avoidance without ACC active that the OP is talking about.

ACC, when active, will indeed bring the car to a complete standstill, and turn off the engine. It will start the engine when the car in front moves, but won't actually move off until you either tap the resume button or press the accelerator.

And, like others, I've experienced the red light and some pre-braking, usually when I know the car in front is turning. But I've never had the nerve to see if it will actually brake sufficiently to stop me from rear-ending someone.

Thanks johno - very helpful

[Lux700]

Thanks to Johno and SkyJawa for your replies. The ACC stops the car nicely; wonder why the collision avoidance feature isn't designed to? I've tried ACC in built-up areas, but it's all a bit stop start and obviously doesn't anticipate. Pretty good though!

[pete18]

On my other car (mercedes) it will pre tension the seat belts also.

[Lux700]

Originally Posted by pete18

On my other car (mercedes) it will pre tension the seat belts also.

All these features, as well as others we haven't even thought of, will be standard equipment in cars soon.

[ontheway]

Originally Posted by pete18

On my other car (mercedes) it will pre tension the seat belts also.

Mine pretensions the seat belts mechanically in an emergency - Admittedly it was a pretty close call. (before the full pretensioner fire - which I haven't experienced)