91 300E Trans Gear question
 

I have a 1991 300E 3.0L. At 65 MPH the engine is turning approximately 3,000 RPMs. I am getting 25 MPH on highway mileage and 21 combined. Can I have a different top gear installed to drop the rpms and save fuel. This car has amazing torque at high speeds, I am assuming this is so due to the high RPMs. I am not looking for performance. My other cars have similar transmissions w/o overdrives yet still turn at 2,000 RPMs at these speeds. Also how much should this cost to do? Thanks JRR

You could go with a different rear end.Cost you find rear end and mechanic change $200 to 1000.

Why spend $1500 to gain maybe 1-2mpg at best?

Our 1992 300E - catalytic convertor equipped - managed 70 mph at 3100 rpm ish.
Two more gears would have been useful, however they were designed for the autobahn and left at that. 110mph comes up at roughly 4000rpm on one of those, btw.
I haven't heard of an automatic gearbox upgrade for the M103 engines, not even in Germany.

I have driven two of the same cars and they both drive identical...high RPMs in 4th gear but smooth and powerful. Seems like it should shift into 5th but never does:)