That advertised speed seems to be ground speed, the trick is that they designed this thing to fly very high where the corresponding IAS is much lower. What's ne

That advertised speed seems to be ground speed, the trick is that they designed this thing to fly very high where the corresponding IAS is much lower. What's new (and a truly surprising as impressive technological achievement!) is that they do this on a piston engine which are notoriously less capable at high altitudes than jets or turboprops. An implication of this is that short-haul applications will see neither the speed more the mileage advertised. I still want to see the general design principles applied to the problem of regional feeder flights, it won't be quite as over the top impressive but it would still be the closest to "slow steaming" available (speed really doesn't matter on feeder connections where boarding alone takes longer than the flight, but it's very hard for aircraft to trade speed for efficiency once non-negligible payloads are involved)