Hello Friends !

Hello fellow campers. New to forum.
Thinking about buying a Class C motor home for my retirement life.
Going to look at a 2004 Sunseeker 2600LE setting on a 3500 Chevy chassis. Motor is a 454 fuel injected. Has anyone bad things to comment about these motor homes ? I'm wondering what fuel mileage to expect? Owners claiming 15-17 mpg , sounds high to me.