My 89 4 speed GL camper will get 20/21 mpg if I travel at 55 mph and don't
have to deal with large hills or mountains. If I travel at interstate speed,
(70mph) the mpg drops to 17/18. These mpg figures represent driving an empty
van.  No camping gear, dog, full tank of water, etc.

BTW, I'm having a Boston Bob engine installed soon and am eager to see how
it will perform. My stock engine finally developed a bad rod bearing at 174,
000 miles.