My 95 S420 was rated at 15 city/20 highway. That's about what I got. I was impressed that it would hold 20mpg on the highway even with extra weight in my right shoe.

I'm impressed with what I read about S320 fuel efficiency. My 91 300SE was rated at 16 city/20 highway. Reality was more like 17 city/19 highway. Tells you something about how unmatched the M103 is to the W126.

Sixto
87 300SDL