Class A vs class C

Mileage keeper shows my C (E-450, 30', heavy with 2 slides) averaged 8.2 MPG over the past 30,000 miles. Individual tanks ranged from 6 MPG to 12 MPG, determined mostly by speed throughthe air, whether determined by road speed or headwinds and tailwinds. A 30mph tail wind will do wonders for MPG on a 70 mph road. A 15 mph headwind will kill MPG when you are going only 55. But it all averages out, in the longer term.