Skylark4.
I think you've hit the nail on the head there, Diesels are definately the way we'll be going, but unfortunately development seems to be very slow because it seems to be mostly driven by small companies in Europe cos we all know about the outrageous cost of AVGAS here. In the states both Continental and Lycoming are working on JETA1/Red diesel powered piston engines but mainly in the 200BHP plus range. I'm no engineer but I'd have thought that a certified, reasonably priced engine to replace the Lycoming 0-235 or Continental 0-200 to address the retrofit market would clean up! I'm definately keeping a close eye on the Wilksch but as I understand it there is no plan to certify the WAM120 in the near future. I reckon the possibility of reducing your fuel bills by around 60% would be something that most Flying training organisations would snap up.