RG5384 is correct about the 300SDL's mileage. My commute is 60 miles each way and I routinely get high 20's MPG. Plus, the car really doesn't ever lack power once she's moving. The first 20 feet or so is rough, but as soon as the tach hits 2000rpm, it moves quite nicely.
I've got around 270k miles on mine and it runs great.
Good luck in finding a car.
Sold: 1987 MB 300SDL, 320k miles, Astral Silver, Blue Leather, all books and records from day one.
Totalled: 1998 VW Jetta TDI, 488k miles, Classic Green/Gray Leather, loaded, E-Codes, "Slightly" modded, "Slightly" faster than stock, arrived 11/07/1997.
MBCA Member, Chicago Region