I am sure this gets discussed a lot, but I am going to ask anyway.  I am 
still tuning up my newly acquired '80 Vanagon Camper and trying to gauge if 
it is running properly.  What kind of gas mileage should I expect from it on 
the highway (relatively flat) without any water in the water tank and only 
two adults in it ? 

 I used to have a '71 VW camper  and I would get about 18 MPG if I remember 
right.  I spoke to my brother who USED (can't believe he got rid of it) to 
have a '91 VW camper.  He said he usually got about 15 MPG going 60-65, 13 
MPG if > 70 mph.  In the city he said it got about 13 MPG.

I have seen some discussions about the non-linear fuel gauge.  I guess VW 
still didn't get it right.   My '71 would never stay full.  It seemed to 
stay about 1/2 full most of the time and when it starting getting near E it 
would drop off in a hurry.  On my '80 it just seems to drop off in a hurry.  
I haven't run it all the way down yet, but it is getting a 100 miles to the 
first half of the tank.