I debated awhile before posting this due to an obvious conflict of interest between the author of DieselAir newsletter who just wrote about the future of avgas, and his past consulting work. Andre R. Teissier-duCros was a consultant to an Atlanta company called DieselAir Aircraft formed to equip Cessna 182 aircraft with the SMA line of diesel engines, but the company no longer exists, according to former CEO Leonard Harris. Teissier-duCros is also publisher of the DieselAir newsletter. That said, I checked his background and decided his expertise is worth considering. The bottom line of his survey is this: a lead-free, ethanol-free alternative to 100LL will be available in five to eight years, but it will cost $10 a gallon. That price, the prediction goes, dramatically reduces the general aviation fleet. Manufacturers will begin equipping piston-engine aircraft with diesel engines–especially for fleet sales to flight schools. Many aircraft owners will switch to mogas, and the light sport aircraft equipped with Rotax engines actually prefer mogas. Those that can afford the $10-per-gallon price will continue to fly with the more expensive but environmentally friendly fuel, but will eventually convert to diesel engines when one is available for their make and model. Is that the truth, or a dream found in a PowerPoint presentation on the floor of the SMA board room? Teissier-duCros says it comes from his worldwide survey of opinion.