This looks very interesting. You get better climb rate, a little slower cruise, but much more efficiency and range! At 2400 TBO they just R&R with new engine within a week. 172R Climb Sea Level to 12k: 31 min, 5.4 gal, 170 fpm Max Cruise Speed 12k: 117 Fuel Flow: 7.9 gph Range: 640 nm 172S Climb Sea Level to 12k: 28 min, 5.0 gal, 220 fpm Max Cruise Speed 12k: 119 Fuel Flow: 8.9 gph Range: 560 nm 172 Cenutrion 2.0 Climb Sea Level to 12k: 26 min, 3.2 gal, 314 fpm Max Cruise Speed 12k: 111 Fuel Flow: 5.3 gph Range: 1000 nm http://www.vanbortel.com/Thielert_Information.htm What do you think? If my longest flights will be 420 nm, not sure what it will get me except saving fuel costs. Would this type of fuel be harder to come by and more expensive? Anyone know how much this engine would cost over standard? If gas prices keep rising, this might not be a bad idea. Lower the weight of fuel you carry too.