Modern European turbo diesels get more than 60 MPG as a matter of course."
I have read that 40 to 70 percent of new vehicles sold in Europe now are diesels.
We do NOT get diesels in the US for BMW, Audi, VW, Mercedes, etc. But they make some good, high performance motors.
And Audi just won the 12 Hours of Sebring in a Turbo Diesel motor--very, very fast reliable race car.
Both diesel and turbocharge technologies yield high torque at low rpms. Stump pullers.
http://www.airliners.net/info/stats.main?id=403
Have a look at that link, should lead you to an Austrian light twin aircraft, the Diamond DA-42 Twin Star.
Twin turbo diesels.