MPG for Various Class A Motorhomes

I get between 5 and 6 (OK, 5.5) no matter how fast I drive. Now, I have to admit that I have never driven 55 for any length of time so mostly 62 to 72. I would rather poke my eyes out than poke along at 55! Even if it were the difference between 5 at 70 and 7 at 55 MPG I would not never choose 55. Let's do the math. An extra 2 MPG over the average 10,000 miles driven by RVer per year. That means you get to drive an additional 2 miles for every gallon of gas used. 10,000 miles divided by 7 equals 1428.6 gallons of gas. 10,000 miles divided by 5 equals 2000 gallons of gas. That's a 571 gallon savings over the course of a year. Maybe $2000/year savings but it took you an extra 666 hours to get there. It's about balance. $2000 is a lot of money but time has value as well. I like to "be there" more than I like "getting there".\
YMMV!