My 29' Rockwood class A gets 5-6 MPG. Gas to Glamis is about $300 bucks just for the RV how can I make it better? Chevy 454 stock with headers and flowmasters. Any suggestions?
What year?
My 1985 Pace Arrow can pull down up to 12-13 MPG towing if I drive it like an old man, I have a 468 Chevy built like a MOFO with Air Research TBI, Jacobs ignition and a Banks exhaust system. It even still has a working EGR valve on a Performer intake...

Like Beav says, drive 55-60 and it will do pretty well, motor homes punch a big damn hole in the air...Follow big rigs as close as you can and see how pissed they get

BTW, Mine is a 26' class A with the HD package (19.5 wheels, full air bag, four wheel disc brakes...)
GT