1. Avgas is the only leaded fuel around here. Since the airplane fuel usage vs. automotive usage is just a drop vs. ocean. Not only ecology but also oil rafineries will drive out avgas - (not all engines can accept Mogas).. .2. Current piston engine designs are unbeliveably obsolete,(thirsty, ecollogicaly unacceptable, heavy) Nor Lyc nor TCM considers any radically new gasoline powered design - they even work on their own diesels (maybe to little, too late). .3. Small turbine which is affordable, is not achievable (yet). .Considering these facts, SMA (Renault), Thillert...diesels are the way we will go in piston engine powered aircrafts.. .First Tillert conversion is hopefully coming to an aeroclub nearby - I`m barely waiting to check it out!. . Mihael