I get 31-33 MPG. As far as the major contributing cause for loss of compression...320,000 miles on that engine speaks for itself. "Normal" wear is a fact of life for any engine (diesel or gas). Regular oil changes and good clean fuel go a long way in assuring many troublefree miles. One of the benifits of the diesel engine is that it is relatively maintenance free compared to a gasoline powered engine. Diesels are however more expensive to have worked on when they do need it. Mostly I think because of the scarcity of knowledgeable maintenance people (high demand). But for $800 bucks...what a deal! Drive it till it dies and bury it you'll still be money ahead. Or you may fall in love with it like I did while you are patiently waiting for it to die!-Good luck.