Don't hope for much more than 15-17 in town if you see traffic. The 6's don't do much better than the 8's because they have to work far harder to move the car.

You can get 18+ in town if you don't mind allowing the rest of the world to pass you by each time the light changes or the traffic moves forward on the freeway. Here in Houston, if you don't keep up you get run over.

I've seen 23 or so on the highway - extended run at 75 with the cruise on. Load it it up with passengers and lose 3 or 4 mpg - again, the 6 can't take the extra load without sacrificing mpg.

Keep the car under 80 and they do OK. On my '92, the VVT kicks in at 3,000rpm, which is just over 80mph in 5th gear. Once you hit that mark, mpg drops into the crapper.

One of the biggest killers of mpg around town is the forced 2'nd gear start. Takes far more pedal to get the car moving, consequently a higher shift point to 3rd - I routinely see 3000+rpm before the shift to 3rd. If I start it in first, with a fraction of the pedal required for 2nd gear start, I get the same acceleration, and a 2-3 shift at about 22-2500. I'm almost dead positive that would result in better fuel economy - but there doesn't seem to be any way to get this car to start in 1st without manually shifting to 2nd at each stop. Every avenue I've travelled to get FGS has been a dead-end street.

As crass is it sounds - if you're looking for MPG, don't go shopping for an S-Class - especially a W140.