Thanks to all for your input!

I guess I was hoping to get more like 30 mpg with the manual transmission.

I have changed the filters, and will check the return line to the tank.

When I got back to town from picking it up in Dallas, I was determined to get the oil changed ASAP. My independent was golfing that day, so I took it to the Mercedes dealer. The service writer and several mechanics all crowded around to take a look at it! They could not believe that it was in such good condition. That made me feel good.

Thanks again.

George