Adding my experience to the observations of others, My '84 Auto Vanagon
gets ~22 driving open highways in the midwest, my '88 Auto Vanagon gets
~18 under the same conditions.  I think the 1.9 vs 2.1 displacement is
the difference.  I've had similar experience with with other vans.  My
'86 "good" Westy gets no better than 20 driving it the same way, and
it's a Westy without the stove/fridge, etc.

Chuck Hill