The cruise on my '80 450sl (45,000 miles) seems to work fine with one exception. It continually loses speed over a long time. As an example I will set it at 65 mph and over the next 50 miles it will be down around 62 mph. Once I speed up and reset it it does the same thing. Not sure how far it will drift down but it is a bit annoying.
Is there a setting or potentiometer somewhere on the control unit that will get it to stop drifting like this?