"The Older Gentleman" wrote

Are there any diesel aer-engines, or diesel car engines frequently used
in aircraft? I had the impression that diesel aero-engines died with
airships and the Junkers 86, but I'm always willing to learn....

Check out Diamond Aircraft
http://www.diamondaircraft.com/aircraft/index.php

They had problems with their engine supplier going bankrupt, and were left
without support for their engines, but have gotten another engine program
going quickly. I can't recall if it was the Mercedes engine that went belly
up, or if they are going to a Mercedes engine.
--
Jim in NC