B+ motorhomes

I was curious about my gas mileage ( never checked all last year after we bought ) and on this trip from Winchester to Erie we got 14+ on the first leg to Pittsburgh. I had told people that had asked before that I guessed about 12. I've have slowed down to 60 on the interstates but even driving at the speed limit and over last year, I was always passed by everything else on the road.