Great post overall.<p>A few nits I&#x27;d pick. Even though 70% of the fleet could burn 94UL, that represents well under half of the gallons burned. Turbocharged engines (often in twin engine airplanes) fly far more hours than the average 7.5:1 compression piston single. Yes, flight school aircraft on the low end fly a lot, but most piston singles average under 75 hours per year and often at 8-9 gph. Turbo singles, IO550s (Cirrus and Bonanza), and turbo or IO550 twins are typically burning 1.5x that per engine and flying 2-3x the hours.<p>I think most of the engines that can&#x27;t be easily modified to run on 94UL are concentrated on the expensive end of the fleet. Most 182s&#x2F;172s&#x2F;Cherokees&#x2F;G-cats, etc can either already run today under the Petersen STC or could be easily modified. It&#x27;s the Bonanza, Cirrus, Golden Eagle, P-Navajo, etc that need 100LL (or GAMI or similar) and can&#x27;t run on 94UL. Those tend to be way more expensive than the lower end of the fleet.