I currently commute approximately 180 miles a day. I have a 78 300SD and a 91 350 SD. Both are good runners but don't get the best fuel mileage. My 78 300SD does approx 24mpg while the 91 350SD does approximately 22mpg on the highway.

the commute is primarily highway (90%) at speeds of 70 - 80 mph. While the vehicles take the running with no sweat it does cost a little.

I have been thinking about a 190D 2.2 for this purpose. I hear that they are great on fuel mileage and have decent torque for such a small engine.

Any thoughts. They're hard to find but it can be done. Anything to stay away from?