My car is trying to kill me...

[hshah]

So I have Adaptive Cruise Control (ACC) in my new BiTDI and I swear it is out to get me. So many times it has tried to ram me into other cars, so much so that the distance warning thing has popped up before I have stepped in and slammed on the brakes.

Just today, I had set it to 30mph whilst sitting in traffic and whilst slowly moving along at 10mph I decided to change to a lane that was empty for about 5 car lengths. My car decided that it was a good time to speed up to around 25mph right towards the back of a lorry. I had to brake so hard that the ABS kicked in.

First thing I did was check the radar domes at the front and they are clean, so its not like it didn't see the lorry right in front of it. The only thing I can think of is that my car is out to get me :(


On a separate note, the journey was only 9 miles and travelling no faster than 40mph and no heavy braking other than the incident above. When I got out the car there was a lot of heat coming from the offside rear tyre area. The nearside rear tyre area was warm but not as hot as the offside... you could feel the heat as you walked about past at about 0.5m away from the car. Is that normal? I am guessing there is something in that area that gets warm?

[zollaf]

i think you need to take your car to a garage . the wheel being hot indicates the brake is sticking on, so that needs sorting. the acc problem could be a lot of things, you need it plugged into a computer to see whats up, or just turn it off and drive normally. but the brakes need sorting out.

[belly buster]

Was the lorry moving? The ACC will adjust your speed to other moving vehicles, but not to stationary objects.

Check the tyre pressures if it is the tyre getting hot.

[hshah]

i think you need to take your car to a garage . the wheel being hot indicates the brake is sticking on, so that needs sorting. the acc problem could be a lot of things, you need it plugged into a computer to see whats up, or just turn it off and drive normally. but the brakes need sorting out.

I need to book the car in for the start stop kicking in before the car has come to a full stop, so will add this to the list. If the brake was sticking would I be able to feel it whilst driving (I can't feel anything odd)?

[hshah]

Was the lorry moving? The ACC will adjust your speed to other moving vehicles, but not to stationary objects.

Check the tyre pressures if it is the tyre getting hot.

It wasn't moving, but surely if it sees something in front of it the ACC shouldn't try and plough me straight into it? Even when driving and the car in front slows down suddenly, the distance warning has popped up and that has started braking the car instead of the ACC braking. Whilst the ACC is useful I don't think the programming of it is that good... it doesn't gauge how fast the car in front is moving away. For example if the car in front suddenly speeds off and then slows down again, my car will speed up until it is too close and then brake sharply.

Tyre pressures are fine, I usually check them once a month and the last check was last weekend.

[zollaf]

you won't always feel a binding brake, but you will feel the eat coming off it.
whilst all these electronic driving aids are nice to have, nothing beats actually just driving.

[belly buster]

It wasn't moving, but surely if it sees something in front of it the ACC shouldn't try and plough me straight into it? Even when driving and the car in front slows down suddenly, the distance warning has popped up and that has started braking the car instead of the ACC braking. Whilst the ACC is useful I don't think the programming of it is that good... it doesn't gauge how fast the car in front is moving away. For example if the car in front suddenly speeds off and then slows down again, my car will speed up until it is too close and then brake sharply.

Tyre pressures are fine, I usually check them once a month and the last check was last weekend.

The ACC is good but you have to understand how it works to get the best out of it. The ACC works by "locking on" to a moving vehicle immediately in front of you. So if you are in a traffic jam behind a car, it will happily follow that all day, even if it stops and starts.

But when you move lane, it has to lock on to a different car to work. If the car (or lorry) in the next lane is stationary, it won't lock on to it. The same happens if you are coming up to a queue of stationary traffic. You must override it and slow yourself, and re-engage the ACC when the car ahead starts moving.

Once you understand this you'll enjoy the ACC without the heart attacks.

[ukgroucho]

Don't know about the start / stop (which definitely sounds "wrong") or the ACC.... although they could be related to each other via a common sensor of some sort.

Are you sure the extra heat that you noticed was not a DPF regen? They are very noticeable because of the extra heat but also a "fan running" sound from the engine bay.
On the road you will notice the car hanging in a slightly higher gear than usual to keep revs (and exhaust manifold temps) up.

[hshah]

The ACC is good but you have to understand how it works to get the best out of it. The ACC works by "locking on" to a moving vehicle immediately in front of you. So if you are in a traffic jam behind a car, it will happily follow that all day, even if it stops and starts.

But when you move lane, it has to lock on to a different car to work. If the car (or lorry) in the next lane is stationary, it won't lock on to it. The same happens if you are coming up to a queue of stationary traffic. You must override it and slow yourself, and re-engage the ACC when the car ahead starts moving.

Once you understand this you'll enjoy the ACC without the heart attacks.

Even in slow moving traffic my car has gotten so close to the car in front that the distance warning has kicked in and braked sharply to prevent a collision. I think ACC is useful when there isn't much traffic and you are doing a steady speed, but as soon as it comes to stop start traffic I wouldn't trust it.

[belly buster]

Even in slow moving traffic my car has gotten so close to the car in front that the distance warning has kicked in and braked sharply to prevent a collision. I think ACC is useful when there isn't much traffic and you are doing a steady speed, but as soon as it comes to stop start traffic I wouldn't trust it.

I've never had any issues in start/stop traffic - I'd suggest you add it to the list of things for them to look at when you take the car in.

[Holymoly]

What with start/stop, ACC, lane assist and city braking it's all witchcraft to me...


https://www.youtube.com/watch?v=vt20UnkmkLI

[isleaiw]

I need to book the car in for the start stop kicking in before the car has come to a full stop, so will add this to the list. If the brake was sticking would I be able to feel it whilst driving (I can't feel anything odd)?

According to something I read about the facelift, the start stop technology will now kick in when the car goes below 4mph so it is not wrong that it kicks in before the car is stationary.... although how that works with an auto I have no idea, surely the transmission will bring it to a sudden stop.

KR
Ian

[hshah]

According to something I read about the facelift, the start stop technology will now kick in when the car goes below 4mph so it is not wrong that it kicks in before the car is stationary.... although how that works with an auto I have no idea, surely the transmission will bring it to a sudden stop.

KR
Ian

Exactly, your head lurches forward as the car suddenly stops because you aren't expecting it.

Car is booked in for 10th September to have all the mentioned issues looked at. Next month because I'm out of the country after next week for 3 weeks :)

[morski]

I need to book the car in for the start stop kicking in before the car has come to a full stop, so will add this to the list. If the brake was sticking would I be able to feel it whilst driving (I can't feel anything odd)?

I had the same issue whilst mine was in at the ********; the FL A6 i had twice stopped the engine whilst i was still in 2nd gear and trying to accelerate out of junction. Very dangerous and un-nerving. However my own bitdi has never done this.

[A6S]

I think like anything it probably takes a bit getting used to.
the stop start is a lot more aggressive in the fl compared to my pre fl.
the first few weeks like a few have said here it can kick in unexpectedly but once you are familiar with you kinda know when it's gonna kick in. Well at least that's how I feel. It's worse when it's in efficiency mode. Also don't stomp on the brakes as that shuts the engine down too.
My main problem isn't the stop start it's the gearbox. Sometimes it can take forever to drop a few gears and when you need it to overtake tractors etc on a back roads but sometimes it's fine and works as expected.

[Greedy]

Only had my FL A6 for3 weeks but do find the S/S very aggressive. Have got into the habit of knocking the shifter back in to Sport mode at roundabouts and T junctions, stops the S/S activating and makes for a nippy get away in moving traffic compared to sluggish D mode, means I can it leave in Efficiency mode rest of the time and benefit from the coasting which I can do quite a lot of on my commute.

As for ACC then wouldn't use it in stop start traffic as that's not the purpose it was designed for. In testing (another brand) we had someone come off a motorway behind another car and stop at the lights, they pulled off in different directions and he entered a 40 limit but the car proceeded to accelerate towards 70 because he forgot the ACC was activated.

[Sam]

https://www.youtube.com/watch?v=aNi17YLnZpg