Is Class A smoother ride then Class C and MPG

My Palazzo 35' diesel pusher gets about 9.8 pulling a horse trailer at 70mph and I have seen over 12 with no trailer and driving in the low 60's. Speed definately affects mileage. Weight, not so much. I pulled a Taurus on a dolly for a 4,000 mile trip running mostly around 70 and got 11.1mpg. These numbers are all from the trip computer which may be a little high but it is hard to figure exact milage anyway since I boondock a lot and the generator runs off of the same tank. The Palazzo was criticised a lot when it first came out but I have not had that much trouble from mine and have not heard any other complaints lately. There are other coaches built on the same Freightliner chassis that should turn in similar numbers. I do like the air suspension, partly for the ride and partly that I can deflate it when parked and have the coach much lower than many others that I have seen. This rig weighs around 23,000lbs by itself when loaded for a trip.