I have a 89' 300E. It is a 4 speed automatic that seems like it really needed a fifth gear designed in to it. When I am doing 80 MPH my Tach is at 3300 RPM. That seems high. I could understand if the car had awesome bottom end geariong but it does not. I have a 3.0L Jeep Liberty and at 80MPH I am almost a 1000 RPM less than the benz. Is it just the design of the benz or a problem.?

 

I wondered about the same on my 89 300E. This is by design. Has something to do with the torque and power curves of the engine.

 

It is correct. Same here on 88' 300TE. The RPM at the same speed varies from model to model even at the same brand fos cars and I guess this is due to different factors of engineering mostly the differential ratio.