Have a 1983 300SD -- get a mere 15.5 mpg. Spoke with another owner of same make and model, and he said he gets over 25 mpg. I'd be happy if I could just get 25 mpg. Anybody out there with any ideas on how to accomplish better mileage, please let me know. And if any of you have experience working on diesel engines and live in San Francisco or nearby, please let me know if you'd be willing to help me improve my diesel engine's performance.