The Green Machine (1995) has a carb'd 454 with a 4 speed overdrive tranny and I get around 10 mpg. As Daveinet stated, the real problem with older MHs is rust. My bus has just 40,000 miles on it but most everything on the underside has rust. The previous owner replaced the exhaust system, yet the tailpipe has rusted through again. The genny muffler is patched now and will be replaced this winter. Most of the basements leak, and if I were going to keep this rig, I'd be replacing the genny, re-sealing all the storage compartments and rust treating or replacing the propane tank.
