Hard to believe...
I recently went to Lake Texoma in Oklahoma to visit a friend, and there happens to be a gas station next to the airport. The Rotax 912 engine can burn car gas, so we filled it up and I came back. With one passenger, we were a full load.  {Note:  we have discovered since then that car gas makes Evie go crazy, so we quit using it!}
When we arrived at Georgetown (KGTU) and I filled it up, I was shocked to see it only took 8 gallons. Distance was 240 miles. 
So we got 30 MPG - going 110 Miles per Hour!