I've been dealing with cruise control issues in my 2022 S 500 Mercedes for the past year or so and have brought the car in for service at least a dozen times to address these issues. I have also written numerous emails to Mercedes-Benz corporate and sent pictures showing the cruise control wanting to speed up to 80 miles an hour on a 55 mph highway and also wanting to reduce down to 10 miles an hour on a 55 mph highway. I sent all this documentation in the emails to Mercedes-Benz corporate in the last three months and they finally got back to me today with a determination. They have determined, in their infinite wisdom, that my car doesn't qualify as a lemon nor will there be any remedy to repurchase or replace this vehicle which is a danger on 4 wheels and an accident and or a fatality waiting to happen!!

 

Have you tried to address this issue with your dealership first to see if they can fix it? If so, what did they say?
How often does all of that occur?

The cruise control in all my recent Mbenz cars was flawless. It's the lane keep assist that it's not that good, but the adaptive cruise control behaves really really well.

 

You should describe these scenarios in much more detail. There are several possibilities for sudden speed change where the car actually behaves as it should. Examples being maps database errors when this info is activated for cruise control (I cannot remember the correct name of the feature). Another one is a speed limit sign like poster or sign at the rear of a truck etc. Incorrect braking can happen from challenging collision avoidance situations.

 

It sounds like you have "Maximum Permissible Speeds" enabled in your MBUX interface. This causes Distronic to read speed limit signs, and it can on occasion misread them. I typically disable this anyway. Turn that off, and it shouldn't do this.

 

Shouldn't they attempt those suggestions as part of the diagnosis process? But of course in actuality customer service is so hands-off nowadays.

If that doesn't work, set up a dashcam suction mounted to the moonroof to capture all of the controls and screens. Nothing speaks like video.

 

Agree on this. With this on sometimes it would catch ramp speeds and slow the car down to match the ramp speed. Example ramp speed is 20 MPH, and you pass the exit staying on the highway doing 80, and it tries to slow it down to 20.

 

Every car you buy, by whatever name the manufacturer is using, disable automatic speed limit following. Worst. Feature. Ever.

 

Its a good concept in theory, but theory is far from practice!

 

It's a great idea, a driving aide that should take some of the load off; perhaps save you at a speed trap. In practice, they're just as you described. At least at the current tech state, they get it wrong too often. Even when they get it right, they can get it wrong. Take I-5: Where the speed limit is 70, the flow is doing close to 80. The limit slows down to 60, the flow is STILL doing close to 80.

The latter deal with auto speed following bit me. One fine day, I was leaving Porsche of Livermore in a new Panamera. Doesn't take long to get on the freeway from there, and I hit the cruise, while I was sorting out some other crap. Wasn't my first Panamera, so I knew what to do, but I hadn't got to fiddling with the cruise settings, when the speed limit slowed down 10 mph, as did the car. Don't know if you've ever experienced it, but with Porsche, it slows down stupidly quick at a limit change, when speed following is enabled. Not an easing into the brake, it downright brakes like it means it. Traffic, of course, didn't slow down at all. In any event, the car behind me was a wee bit surprised by my sudden braking for no apparent reason, but thankfully, was paying attention. He went into ABS, but didn't hit me. He soon went around, and I could see his lips moving, but not hear what he was saying: Based on his demeanor, it wasn't complimentary. O_o

In any event, I've yet to have one that wasn't irritating at best.

 

It’s interesting how we see different value in some of these features.
To me, this is a MUST HAVE feature in every car I own or will own. I love it and use it literally 99% of the time while driving. It works well for me even when it misreads signs (which rarely ever happens anyway).

 

Fair enough. I would however say that I could have gone much further than I did...

You've got school zones, the ones where you slow down when children are present, or the light is flashing, or between the hours of X, all of these, will be wrong more often than they're right. Same with construction zones, and around here, they're seemingly everywhere. In this state, with some you need to slow down only when people are working, others are around the clock speed changes. It will also occasionally read signs on a road running next to, and parallel the road you're on. That usually happens on the freeway, it doesn't often happen, but happens. You've got that pesky speed change that occurs when you turn off of one road, and on to another; sometimes it gets it right, sometimes not. Sometimes signs are blocked by traffic in between you and the sign, by a truck/trailer comb for instance. Usually you've got GPS backup, but that often doesn't kick in until you're past the point where law officers like to lay, directly after a speed change. Can't forget those speed caution signs, you're not required to slow down, most people usually don't, because the majority are mild curves, and the advisory is more to wake you up to the fact you have to move the steering wheel, than anything else.

On the flip side, it's more often than not, doing nothing anyway. When I'm at the Seattle apartment, all across town, on my way to the freeway, the speed limit will be 30, outside a few roads where it's higher. Once on the freeway, you've got the pesky dynamic I already described. When up at the Island house, I'll often get on the highway going North, or South, there, the speed limit is defined by the flow of traffic, and your automatic speed following is simply the car in front of you. Otherwise, when not traveling up or down the Island, in the same way as Seattle, the speed limits seldom change as you go about your business in town.

I'm a techy sort of dude, I like new stuff, playing with the toys. I have tried to learn to like it in every car I've owned, that had it. I do have hope for it, but for me, it needs to get smarter. When I use it, I am given more work preventing it from switching to the wrong speed limit, than I save with it doing ithe changes automatically. I don't score that a win for automatic speed limit following.

 

I would like it if it would allow a buffer above the speed limit. On top of the fact that I don't want to drive the speed limit, you really can't here, the flow of traffic is considerably higher. For instance if I'm on a road that has a 65 MPH speed limit, the flow of traffic is 75-80. I would set my cruise 75-80 depending on the road. Then that road goes down to 55...but the flow is still going to be 10-15 over that if it changes at all, but the car slams on the brakes and hauls me down to 55 which isn't safe behavior on a road with other drivers. If it would gradually slow me down to 65 or 70 I would like it.

 

Yeah I am not sure what's going on with the speed buffer/offset. I know Tesla uses that (% buffer or absolute +/- value), but Mbenz never had it, and on the other hand, BMW removed it in recent software updates. They used to have it in all BMWs I had between 2019-2023 (2 speed adjust ranges/offsetts, one for lower and one for higher speeds), then sometime in 2023 all software updates blocked that feature and pushed it to a "hidden" menu here in the US. I had to code my cars to show that menu again in the cluster. I believe the software updates removed that only for US cars, but they were still developing the menu (including Stop sign and Traffic light response in europe which improved really over time since then and I was able to get that as well even on my iDrive-7 cars). I can still code it easily in 2025 and works well, and I set it for 5 MPH offset above 40MPH, and 4 MPH below 40MPH. As far as speed sign recognition, what's different between Mbenz and BMW is that the speed is adjusted in my BMW well below I arrive the speed sign (the car starts to reacts at a reasonable distance before I reach the speed sign which is what most humans do, wherein in my GLS and W222 it would only react by the time I passes right next to that speed sign and I admit it's annoying sometimes as it means I may be driving over-speed for a short distance right after the speed sign, so I wish they'd fix that in future OTAs. That got fixed a few years ago via OTA in BMWs, and when I had a Tesla, they also addressed it last year). I hear that W223 gets more serious upgrades/updates/improvements via OTA than the GLS, so hopefully Mbenz will address that instead of waiting for the facelift or new MBUX hardware release (I bet they're lazy enough to NOT fix it via OTA though).

Back to your point, yes, when I drive the GLS, I do miss that offset feature, but often it's just one additional click to increase the speed limit by another 5MPH. I still like that it sets the speed limit to the closest value (kinda better than having to do it all manually). Sometimes am fine with the exact speed limit at least in town. Also, when on highways, not that if you just poke the accelerator the same seconds it starts to slow down, it will ignore the speed limit change and stay where it is (I learned that recently). Kidna a kip feature until the next speed limit sign/change. It responds well around school signs too in-town. It doesn't work all the time, but it works most of the time, and with the accelerator trick I just mentioned, the skip feature is really convenient and even easier than using the steering button to re-adjust (it will just continue driving at the same previously set speed but the auto-change is still active for the next change). Never noticed that it slams the brakes on highways when the speed drops by 20 MPH. It seems to slow down cautiously but we may have baselines standards or driving/dynamic preferences for reactions on highways.

Photo from the web for the same window I was referring to:


Photo from my X7 couple years ago:

Photo from my X7 couple years ago


Photo from my X7 couple years ago

 

Some do let you set a higher speed, Porsche, for one. It's a kludge, you have to reconfirm your over at every change. Worse, you only have a short window to answer a toast allowing you to keep your over, and you have to watch like a hawk for it, or you'll miss it altogether. You still run into the issue of the correct speed though, out on the freeway, you'll be doing 10 or more over, just driving in the flow of traffic, get off the freeway, and that same over can put you in ticket territory. Now you've got to manually adjust your over, to a more appropriate number... It goes on and on.

 

I too use Speed Limit Assist, and on some highways that I drive frequently, the speed drops from 65 to 55, but I often drive 70 or so on those roads. I know when I pass the 55 MPH sign, the car will adjust to the new speed. I've learned if I just tap the accelerator when the car drops the 55, it will retain 70 MPH. When I travel to unfamiliar areas, such as Charleston or Tampa, I find the Speed Limit Assist feature helpful to assist me in avoiding speed traps as Crab mentioned.

 

It's a feature I want to like, I keep thinking the next one, maybe it will be there. While I remain hopeful, it hasn't happened yet.

 

But if I am already clicking I can also just click down 5MPH and it will slow down, and without slamming on the brakes with traffic behind me. It changes the speed in the dash cluster when it reads a sign, and that alerts me...plus I really don't have an issue realizing when the speed limit goes down.

 

Well, that's why it's an option. It's not for everyone to leverage. I see it as a must-have, others don't even want to use it. In most cases I don't need to click/push or engage at all, and that's what I appreciate about it. It's only when I need to keep the offset speed when I need to use it. For in-town, I barely touch it. It also slows down before roundabouts but am not sure if it is related to the speed limit assist or not.

 

You use the distronic on surface roads?

 

I use cruise everywhere. For me, there's no question that it creates more clicks than it saves, and it also causes the car to do the unexpected for drivers around me, to the tune of pushing one into ABS.

However that may be, it seems I was wrong about the never, ever, statement. I've yet to meet anyone in the real world that uses it, most describing it as somewhere between irritating and pointless. I had in my mind the idea that it was one of the features that was used by very few. But in just this thread, there are a couple takers. It seems I stand corrected.

 

I first noticed route based speed assistance when I was traveling back and forth between Yakima and Seattle several times weekly when my wife was hospitalized in Seattle. I was driving at mostly extralegal speeds in her then new 2024 GLE 450 using distronic and the car would inexplicably slow down for curves. It drove me absolutely crazy. I finally realized that I had enabled route based speed control. That was in August of 2023 and I haven’t used it since. I may try it again if you can resume your set speed by merely tapping on the accelerator. I’ll give it a try.

 

My lemon law attorney told me "Manufacturers are not in the business of buying back cars". Lawyer up if you wat to go that route, but know it's a long and painful process.

 

Or live in California I guess, much easier lemon law process.

 

All these added safety items are making the cars more dangerous.
personally I’m not going to spend 50k+ for a car that has every assist under the sun. Turn it off and drive with your common sense.
I just came back from a 1200mile round trip, didn’t even think once to turn on the cruise control. Enjoy the car man
disable all that useless crap.

 

It will be great if you have all these assist systems... but they let you turn it off.

I mean paying for a MB, you do expect to have as many safety assist features as possible, economy brands already have these basic things. Having the option is good but please let us turn it off if we don't want it, and keep it off if you insist.

Otherwise, maybe not option DISTRONIC when ordering, not ideal though as there are other safety features as well that you will be missing out, it is one complete suite. Some are useful to prevent or mitigate damage from an accident for example.