Hello,

I usually drive with the cruise control on when in the highway. The system is nice enough to detect speed limits and adjust the car's speed.

There is this highway close to my home (tangential di Milano) that has speed limits specific for trucks. This particular sign is the same as a speed limit with the addition of a regulatory sign that specifies that the speed limit applies only to trucks.

In conclusion the speed limit signs alternate between 90km/h for cars and 70 km/h for trucks.

The GLS ignores the regulatory sign and suddenly slows down, then sees the sign for cars (90km/h) and accelerates, then again a speed limit for trucks comes and speed is down to 70km/h. This is annoying since cars do not expect my car to slow down all of a sudden ...

I tried to tell an Italian MB retail shop about this issue and they told me that the GLS computer did not record any anomaly so the car was fine ... no comment on this ...

Any one has a suggestion on how to report this to MB so that they can think about a fix ?

 

Strange, but I experienced that problem for the first time yesterday. Usually, the speed limit detection is right on, even recognizing reduced speeds in work zones. Yesterday, on a 200 mile trip on the interstate, the 580 reduced its speed from 75 to 55 three times and once cut the speed to 40. Each time that happened, I had just passed a speed limit sign that announced that the maximum speed is 70 and the minimum speed is 40. The speed limit signs in my state look just like the graphic speed limit sign in the HUD, so strange signage is not the problem. In addition, a warning on the instrument screen has been coming on repeatedly in the last few weeks that says "camera view unavailable." And there are no bugs on the cameras.

 

Hi,

could it be that camera unavailable was due to adverse weather conditions like fog and / or rain ?

 

Nope. There wasn't a cloud in the sky on a 400 mile (200 each way) trip yesterday. It has been going on for several weeks now, even on short trips. Can you imagine what would happen if Boeing built its 737 series airplanes with this many software bugs?

 

This system is nowhere near accurate enough to rely on. I would never use it.

 

I have had similar problems, including mine picking up the lower speed limit signs on off-ramps (when I’m not getting off). There is one road I drive regularly that is 90 or 100 most of the time, and in two different spots it randomly starts slowing down (I haven’t noticed what it is slowing to - too dangerous with cars behind me to let it keep slowing down). Very annoying, but I attribute it to the camera mis-seeing something,

 

Piggybacking off your experience, I entered the State Farm safe drivers program. I was penalized for speeding when accelerating when leaving a 35 MPH zone ramp and speeding up to enter the 70 MPH expressway. Go figure.

 

I don't think this is a bug, this is by design and speaks to broader, difficult hurdles that need to be overcome as we inch toward autonomous vehicles.

MB's software likely recognizes both speed limits and can probably distinguish which sign is applicable to you, but there are a number of more nuanced cases where only drivers can make the call. For example, I've seen plenty of signs that say something along the lines of X MPH WHEN WORKERS PRESENT Y MPH ALL OTHER TIMES. Or two speed limit signs stacked on top of each other -- the normal speed limit followed by the school zone limit. The technology just isn't mature enough to distinguish between "workers" and people standing on the side of the road, or determining if school is in or out of session (is today a half-day? does Thanksgiving break start on Mon or Tue?). So instead of guessing, the car plays it safe and goes with the lower limit.

This isn't just a MB thing, and it's not just road signs. When driving you're making one judgement call after another, both consciously and subconsciously. Manufacturers are spending billions trying to figure out how to solve for that. The technology is evolving rapidly but it's not even close to being there.

 

Totally agree with @neetorama . One cannot rely 100% on tech. Otherwise would could all just read a book while driving. I believe this happens to most of us. I have become accustomed to it, and simply just hit the gas and reset cruise control speed. I have also experienced the opposite - while driving over a bridge with a stated 55MPH limit, my GLE suddenly accelerated to 80MPH. I looked at the HUD, and it was displaying 80MPH. Very odd. I never reported it to MB cause they probably wouldn't be able to duplicate it.

 

IMHO, software/systems where a malfunction can lead to an accident are totally unacceptable. How about a brake or gas pedal that works correctly once in a while only?

 

Better to turn off the feature. You don't want the headache of getting rear ended because the car thought it was reading the right speed limit for your path!

 

The automatic speed limit adoption doesn't make a whole lot of sense in the US. I used it in Europe where speed limits change frequently and are strictly enforced. It's very common on the Autobahn for the speed limit to be lowered to 100 km/h, then back up to 120/130 km/h, then unlimited in parts if you are Germany and then back down again and again. Even so, one of the annoying issues in Europe is that lorries (semi trucks for the Americans) have a small speed limit sign sticker on the back with the number 80. It's there to let you know that they are not allowed to drive faster than 80 km/h legally. Unfortunately, the speed limit recognition thinks that's a real speed limit sign and adopts 80 km/h as the speed limit, so now suddenly the car isn't accelerating after changing lanes.

As was said in an older post above. These systems have real world limitations. They follow their programming but lack the intuition and judgment of a human. Getting upset when it recognizes the wrong speed limit is simply a waste of energy. Use it for what it is and if it gets the speed limit wrong at times, just move on. Turning off the automatic adoption of the speed limit is the best course of action to make it less annoying when it happens. I don't even think about it anymore. It's nice to see the speed limit in the instrument cluster, but I don't let it dictate my speed.

In Europe, new cars now must sound a warning if you exceed the detected speed limit. I experienced this most recently in a rental car last October while traveling in Germany and Switzerland. The thing was constantly beeping at me as it recognized the wrong speed limits or if I only went 1 km/h over the detected speed limit. One of the dumbest mandates ever. You are allowed to turn it off, but it's mandatory for it to turn back on between engine starts, so every damn time I had to turn it off to stop being yelled at for going 1 km/h over the speed limit. Stupid, just stupid!

 

Maybe Mercedes already found the fix, try asking the dealer or any Mercedes licensed workshop to try a software update for your camera and maybe MBUX/Comand as the Maps works together with the Camera for predicting the signs

 

There’s no “fix” since it’s working as intended. The only solution is to turn the feature off, which many of us have already done!