Our '85 Class C (26') with a carburated Ford 460 got 6 mpg at sea level and it dropped to around 4.5 at altitude. If you took the gas cap off with the engine running, you could hear the fuel gurgling as it went out of the tank!
Gas was $150 when we got the POS, When it got to $2.25, we sold it (at a substantial loss).
Frank Damp -Anacortes, WA,(DW- Eileen)
ex-pat Brits (1968) and now ex-RVers, as of 08 Dec 14.