Cruise Control and Autopilot Suddenly Decelerates

[jboston17]

I bought a brand new 2022 MXLR in April 2022 that now has about 7000 miles on it. On a couple of recent trips - I have used both cruise control and autopilot (steering assist) and in both cases the car suddenly DECELERATES from 85 to 70 (in the most extreme case, usually it's brief and drops from 85 to 80 or so, but its always jarring in how hard it brakes). I heard they recently went to an 'all camera' system to interpret surroundings and whether or not the vehicle needs to brake or not... So it could be certain conditions (driving into sun, driving up a hill just before reaching the crest, inclement weather, etc) but it has happened to me more than a dozen times in one trip (1200 miles total).

It's incredibly dangerous, not only the sudden slow down and my own reaction, but if there happened to be a car behind me, traveling a bit too close - it could easily cause an accident. This problem is a dealbreaker for me - anyone else have this issue, and have any idea what to do about it?

 

[mxnym]

I've had the happen to me frequently in my 15MS and 18MX. And I recently notice it happening on this new route I take. It appears that there is a section with 55MPH speed limit marked and the Cruise control max speed there will automatically change to 60 and the cars will break aggressively, even there is nobody around me. Curiously, it also happened in my SO's 2023 GLE350 as well, the exact same behavior!

Is this a relatively new route (opened or modified in the last few years)? This type of behavior used to be triggered by "bad map data" (according to service, in 2017), and back then, it wouldn't change the max, it would just slow down and drive well under the max. Either way, the GLE350 behaving the same way in the same spot is curious.

 

[imsachin]

The route hasn;t changed in the 17 years I’ve been in the area….it’s a new route for me on the way to a new job. I’m now looking for of this scenario on different roads where I can test this theory. I personally find it annoying that the max speed changes to something relative to the speed limit signs the car reads without regard to the traffic flow around it.