I owned a 07 Burgman for a while. I had a 35 mile commute one way and most of that was highway travel (not by choice, but the most direct way to work). The Burgie was able to maintain speeds of 60+ without issue.
I was in the 50 MPG range without issue. Highly recommend!
It's nice to see your actually considering the roads you ride. I've found to many people buy a scooter for the MPG without considering the roads they actually have to ride on.