Have Mercedes Questions? Ask a Mechanic for Answers ASAP
Hi, the older Mercedes usually run high rpm at freeway speeds. A simple test is to manually move the shifter from D to 3 and see if the transmission downshifts. Do this at 40 mph after you feel the transmission has finished shifting through the gears. If the transmission drops down a gear when you pull back on the shifter it tells you that the transmission was in 4th gear and that the rpm you are seeing is normal.
Let me know if you have any questions.