While driving our 2017 MB GLE 350-4matic at about 40 mph, it spontaneously downshifted to M1. We were in traffic, so this was a very dangerous for us and for the people behind us. We limped to our destination, not knowing what had happened or what to do. When we re-started the car the next day, it seemed ok. But after driving some distance, it spontaneously downshifted to M1 again. We stopped the car, turned it off and re-started it. My mechanic checked the car with his analyzer, which showed that the transmission was not transmitting/displaying gear changes. I am taking my car to another repair shop tomorrow that has a more sophisticated analyzer. When I first explored this problem on the web, there was discussion on a MB website about similar problems. Today, I saw that there is an NHTSA probe into 2015-17 Ford 150 pick-ups having a similar problem to mine, i.e., spontaneous downshifting. Maybe there is a chip problem in the transmission control module for cars of those years. This is a significant safety issue. Thank God we were going 40 mph and not 60 or 70 when this happened.