Drive car until it warms up and suddenly it won’t go over 20 mph. Let it cool down and it will drive OK for short period of time. Dealership & others have given up on it. Any suggestions? Car is in beautiful condition and only 100,000+ miles on it. Sorry I can’t be more technical.
No check engine light? Could be a number of things. Have you found an independent shop that specializes in Mercedes?
Does the engine rev, but the car won’t go? Or does the engine refuse to speed up?
We need WAY more information
Could be the automatic transmission not upshifting properly, exhaust restriction, etc.
I suspect the guys who’ve given up haven’t performed proper and complete diagnostics. They’ve probably just attempted to retrieve codes, and if there were none, they probably didn’t even know where to start
I suggest asking around for the “go to guy” who specializes only in diagnostics and driveability issues, if there is such a shop in your area
hint . . . it won’t be a new car dealer
Have tried dealership and independent repair. All to no avail. When it happens, it just won’t go over 20 mph. Have been told it’s a “sluggish transmission.”
I don’t know about sluggish, but it sure has been expensive!
how did they determine the transmission was “sluggish” . . . ?
Did somebody drive the car, while monitoring a scanner?
Has the transmission fluid and filter EVER been serviced?
If so, what fluid did you use . . . if not genuine Benz fluid, exactly which brand and what version did you use?
For such an obvious problem these folks didn’t do much, it seems. A ‘sluggish transmission’ is a useless diagnosis. While it might be the transmission, it could be ignition or fuel. A competent shop would be able to figure out the problem. What city are you in?