I have a drive assistance package, and when I hit "resume" when it's already resumed it saves the speed at that location (I believe). This is frustrating when I accidentally save. I drive to that location again and the speed suddenly changes. My questions are.

1. Is my assessment of what's happening correct?
2. How do I clear saved GPS-based cruise control settings?

 

No, that would be a misunderstanding of what's happening. DISTRONIC by default automatically adopts the current speed limit whenever the camera recognizes a speed limit sign. This can be turned off in the settings. I find it not very useful in the USA, but I did rely on this feature during my European Delivery trip to help me avoid getting a ticket from the many speed cameras all over.

On the other hand when you hit Resume when it has already resumed, then it manually adopts the current speed limit. Even if you turn off the automatic adoption, you can always adopt the current speed limit this way. I find this very useful as I use this to initially set DISTRONIC to the current speed limit and then I can adjust it up from there and if the speed limit changes significantly I can always manually adopt the new speed limit.

 

Thank you very much! I was looking all over to clear the memorized settings.

It has the pin icon so I thought it was saving at that location. Also, it was setting itself to 60 in a clearly marked 65 zone, so I doubted that it was reading signs correctly. I will look for the automatic setting, and it's a very nice option to know that the pin on resume sets it to the current speed limit.

Thanks again

 

Remember distronic can fail with the speed limit database too, not only when reading speed limit signs. I find it irritating when the car reads a reduced speed limit (road works etc.) right but then the speed limit info is recorded somehow for sections on the road, probably a new section from a town border (no intersections anywhere near) and the car picks up the "latest" info, i.e. the wrong speed from the database instead of continuing with the info from the camera. Obviously the database is useful when you start driving and the car has not yet seen any speed limit sign.

 

The camera generally takes precedence over the speed limits in the database. It falls back to the database if no speed limit sign has been seen in some time. So on highways with few speed limit signs it is possible that it falls back to an incorrect speed limit from the database. Always make sure the map data is the latest, but of course that doesn't necessarily guarantee that all the speed limits are correct. The map database also has the prevailing speed limits for the different types of roads. Not all roads have individual speed limits and in that case it falls back to the prevailing speed limit for the current road type. The traffic sign recognition is also not perfect. Depending on lighting conditions, dirt on the sign etc., 65 could be read as 60. There have been reports of that. Some recent models also had known issues with plastic gassing out in the camera housing causing it to misread the speed limits.

 

Any more details about this? Our W213 (MY21) recently had some new part within the stereo front camera to fix the issue with several assist features that depend on the stereo camera. Could this be the same issue?

 

Mine was usually spot on and rarely had it wrong, 100% may be too much to ask with the current tech.

I think speed following has significant flaws in any car. Around here with a freeway speed limit of 70 traffic will typically be moving at around 75ish, in many areas it drops to 60, but traffic slows down very little, or not at all. Then there are those pesky conditional school zones, where between a set time or when a light is flashing, you have a lower speed limit. Or construction zones that require a slowdown when workers are present. Or advisory speed limits based on weather. Etc.

There are just too many ways for speed limit following to go wrong for it to be a useful driver's aid, outside some limited uses like ticket avoidance in unknown areas.

 

I haven't followed it too closely, but the gassing out basically causes a cloudy film to build up on the camera lenses and the windshield, impairing the view of the camera. The solution as I understand it is baking the camera housing for an hour at 200 degrees to accelerate the gassing out process and clean the lenses and glass. I don't believe anything gets replaced, but there is an LI for it, so it's a known issue.

When I was using the feature in Europe back in 2019, it worked surprisingly well. Even the conditional speed limits. For example on some of the unrestricted sections on the German Autobahn there are speed limits that only apply when it's wet. It clearly used the data from the rain sensor to determine when such speed limits applied and when to ignore them. The only issue I had was when following a lorry. In Europe, lorries require a sticker on the back that locks like a small 80 kph speed limit sign to indicate that they are not allowed to drive faster than 80. The camera recognized those if I got too close and reduced my speed to 80 kph, usually just about when I indicated to pass them. Not much that can be done about this I suppose, other than enhance the AI to recognize the lorry and ignore the sticker, but I guess it isn't that sophisticated yet.