[TK421BMW]

So did a long freeway drive over the weekend. Loved the 24+mpg. Something I never got with my e70. However when traffic increased the radar cruise was driving me nuts. When the traffic would slow, it would, but would slow more drastically, and not jump back as fast as the cars in front of me. So I'd have 2 car lengths, then the cars would speed up and I'd have 5-6 car lengths, leaving a giant gap for people on the other lane to cut in front. This caused the radar to sense close cars and slow down again, leaving gap.... you get the idea. I started having to slam on the execrator every time traffic sped up. Wish BMW would make it 1 car length and not brake so drastically. In stop and go putting it in sport helps a little, but in this case, 50-70 mph range it didn't seem to.

[MystroX5]

You need to adjust the ACC distance down further. I can tell you from a long road trip that the BMW ACC is the smoothest in the industry. Most system slam on the brakes when getting close to a approaching (slower vehicle). If I set my acc distance for 2 car lengths and 75mph and the pack of cars slows down to 60mph, my X5 locks on to their tail when they accelerate all the way up to 75mph and keeps that 2 car length distance.
Try setting your acc for 5-10mph faster than you really want to go and let it lock onto the car in front of you and see if you accelerate faster when they speed up. I have never had a car in front of me pull away from me if my acc is locked on to them and set at a high mph than they are going.

[TK421BMW]

Shortest it will go is about 2 car lengths. Issue is how quickly it goes from braking to accelerating.

[MystroX5]

Originally Posted by TK421BMW

Shortest it will go is about 2 car lengths. Issue is how quickly it goes from braking to accelerating.

Mine slows very gradual but I have never had a car out accelerate me when it’s locked onto them. That “2 car space” is kept at all times as if a imaginary tow rope is hooked to the car in front of me.

[TurtleBoy]

What driving mode are you in? If you are in Eco Pro it may not accelerate as quickly as the car in front of you but there should not be too much of a delay. In comfort and sport it should keep up fairly well.

You mentioned that the shortest distance is 2 car lengths. It is my understanding that it does not work that way. Rather than a set length/distance it uses an algorithm to calculate the distance based on speed and the distance setting that you have chosen. In other words, the faster you are going the more distance there will be between you and the vehicle in front of you.

[MystroX5]

Originally Posted by TurtleBoy

What driving mode are you in? If you are in Eco Pro it may not accelerate as quickly as the car in front of you but there should not be too much of a delay. In comfort and sport it should keep up fairly well.

You mentioned that the shortest distance is 2 car lengths. It is my understanding that it does not work that way. Rather than a set length/distance it uses an algorithm to calculate the distance based on speed and the distance setting that you have chosen. In other words, the faster you are going the more distance there will be between you and the vehicle in front of you.

You are correct. It’s more like seconds of distance rather than car lengths.

[sygazelle]

Originally Posted by TK421BMW

Shortest it will go is about 2 car lengths. Issue is how quickly it goes from braking to accelerating.

I'm not sure but I thing the change in distance that you can set with ACC is based on time, not distance. When the cars are going faster, the distance increases to maintain a set amout of time in seconds behind the car in front of you.

So, at 2 seconds behind at 70mph, the gap between your car and the car ahead will be twice the gap as when you are going 35mph.

[Grentz]

Personally I love the implementation of it and use it in stop & go traffic every morning. Wayyy smoother than the alternatives I have tried.

I use it with Adaptive and it seems to strike a good balance.

[MystroX5]

Originally Posted by Grentz

Personally I love the implementation of it and use it in stop & go traffic every morning. Wayyy smoother than the alternatives I have tried.

I use it with Adaptive and it seems to strike a good balance.

I do to. Between the ACC and traffic jam, it drives so smooth I don't touch anything but steer.

[mattsrs]

Originally Posted by TK421BMW

So did a long freeway drive over the weekend. Loved the 24+mpg. Something I never got with my e70. However when traffic increased the radar cruise was driving me nuts. When the traffic would slow, it would, but would slow more drastically, and not jump back as fast as the cars in front of me. So I'd have 2 car lengths, then the cars would speed up and I'd have 5-6 car lengths, leaving a giant gap for people on the other lane to cut in front. This caused the radar to sense close cars and slow down again, leaving gap.... you get the idea. I started having to slam on the execrator every time traffic sped up. Wish BMW would make it 1 car length and not brake so drastically. In stop and go putting it in sport helps a little, but in this case, 50-70 mph range it didn't seem to.

I have also noticed similar behavior. When it drives at high speeds (70mph) regardless of how the ACC distance selector (four lines) is set, it breaks so late to the point that every time passengers in the car get worried we may hit the car in front. In slower speed, it doesn't have this problem

[FreddyBMW]

I have driven Audi and now BMW with both having similar issues. Try changing a lane and see how it almost goes to hit another stopped car in front of you in that lane. I know it is dependent on speed and the distance but if my eyes can see a distant car stopped, the cruise (eyes) should be able to spot it as well.

This Tech definitely needs improvements otherwise at times you get more stress from the system than not having it at all at times.

[Charles549]

Originally Posted by FreddyBMW

I have driven Audi and now BMW with both having similar issues. Try changing a lane and see how it almost goes to hit another stopped car in front of you in that lane. I know it is dependent on speed but if my eyes can see a distant car stopped, the cruise (eyes) should be able to spot it as well.

This Tech definitely needs improvements otherwise at times you get more stress from the system than not having it at all at times.

Drive the latest iteration of the system in a new Mercedes and you will know how a well calibrated system works. Tons better than my 50i. Not a MB fanboy, just reporting my observations.

[FreddyBMW]

Originally Posted by Charles549

Drive the latest iteration of the system in a new Mercedes and you will know how a well calibrated system works. Tons better than my 50i. Not a MB fanboy, just reporting my observations.

I heard the same goodies about Mercedes cruise. If these German cars are using the same hardware (I believe so) then they should at least bring up their software to work alike as well.

[ScotsWhaHaeWi]

It's not the slowing down, it's the lag in speeding back up and "defending" your gap from the horrid drivers who pass on the inside and cut in.

It's almost like the algorithm is set for the demonstrably superior average German or European driver, who have actual shame about passing on the inside (and also shame about hogging the passing lane).

The US has such a vicious circle type of driving--can't hew appropriately to the driving lane as passing-lane drivers won't let you in, so you game theory it and stay in the passing lane, becoming the asshole driver you hate. Also drivers don't know that a flash of headlights from a passing lane driver means, "go ahead and move lanes, I got you bro", because it literally never happens in the US.

Anyway, the algorithm is perhaps designed (pure conjecture here) for the German driver and that means a decent gap forms and that means you get screwed by bad US driving.

Solutions? Wait for BMW to improve the algorithm for the US, move to driving-bliss Germany, or be active on your throttle to control your gap. Or just accept getting f***ed by imperfect drivers.

[BimmerTy]

Execution of ACC in the F15 was pretty poor as well. Sounds like it hasn't gotten much better. My 2015 Yukon Denali's ACC works much better - coasts instead of braking (unless necessary) to match car's speed and keeps a much closer distance than the X5 while the closest distance is selected.

[Xeno]

Originally Posted by ScotsWhaHaeWi

It's not the slowing down, it's the lag in speeding back up and "defending" your gap from the horrid drivers who pass on the inside and cut in.

It's almost like the algorithm is set for the demonstrably superior average German or European driver, who have actual shame about passing on the inside (and also shame about hogging the passing lane).

The US has such a vicious circle type of driving--can't hew appropriately to the driving lane as passing-lane drivers won't let you in, so you game theory it and stay in the passing lane, becoming the asshole driver you hate. Also drivers don't know that a flash of headlights from a passing lane driver means, "go ahead and move lanes, I got you bro", because it literally never happens in the US.

Anyway, the algorithm is perhaps designed (pure conjecture here) for the German driver and that means a decent gap forms and that means you get screwed by bad US driving.

Solutions? Wait for BMW to improve the algorithm for the US, move to driving-bliss Germany, or be active on your throttle to control your gap. Or just accept getting f***ed by imperfect drivers.

Having logged another day of a few 100 miles, I am getting more distracted by the limited use of ACC due to the issues described in this thread.

I use the minus control for distance so is there a hidden menu somewhere that will get me closer to the vehicle in front of me?

The settings obviously do not accommodate someone who is used to having to pass on the right at triple digit mph on USA interstates in order to advance beyond a clogged left lane.

I also want to add that the lane departure at 85+ mph is distracting since it constantly bounces around.

[ggalanis]

Originally Posted by Xeno

I use the minus control for distance so is there a hidden menu somewhere that will get me closer to the vehicle in front of me?

Nope.

If you press and hold the minus button, it will turn off the radar component of the cruise control though.

GG

[TurtleBoy]

Makes perfect sense that they will not allow you to set the distance to be closer than the recommended safety distance for the speed you are traveling.

I have used the cruise extensively and have not had any problems with. Seems like that is the experience of the large majority of owners.

[ggalanis]

Originally Posted by TurtleBoy

Makes perfect sense that they will not allow you to set the distance to be closer than the recommended safety distance for the speed you are traveling.

I have used the cruise extensively and have not had any problems with. Seems like that is the experience of the large majority of owners.

I guess some people would like it to get close enough to pressure the driver ahead of you to get out of the passing lane. But I agree that that is not how it is meant to be used.

GG

[TurtleBoy]

Originally Posted by ggalanis

I guess some people would like it to get close enough to pressure the driver ahead of you to get out of the passing lane. But I agree that that is not how it is meant to be used.

GG

The gas pedal still works for that or passing on the right so I don't know what Xeno’s issue is with those.

[Xeno]

I am trying to get close enough that someone will not cut in front of me and so that I can move right to pass the mile of cars in the left lane that I have seen in SC now NC.

OK has a law about not impeding the left lane, but apparently that would be a foreign language here.

[TurtleBoy]

Originally Posted by Xeno

I am trying to get close enough that someone will not cut in front of me and so that I can move right to pass the mile of cars in the left lane that I have seen in SC now NC.

OK has a law about not impeding the left lane, but apparently that would be a foreign language here.

I don’t understand, why can’t you go into the right lane to pass. Nothing in the cruise will keep you from doing that.