Interesting. In the Pioneer I could get 115 kts for 15 litres per hour = 28.75 miles per US gallon. The new engines and hull designs are certainly more efficient that the older engines, even mated to a modern hull like a Vans. The difference is quite striking: £0.15 per nm for the Pioneer; £0.33 for the Vans (rough averaged figures). The cost per hour is about £18 vs £51 allowing for higher Avgas prices.
Remains to be seen how the 1000s of Rotax and Jabiru engined aircraft deal with bio fuel in Mogas
Start to run on avgas and the higher price eats into the savings, especially when factoring in reduced service intervals to get rid of all that lead. Then when Avgas disappears..........