I bought my Chevy G20 van new in Nov. 1975 and we're still using it to carry the large loads or for hauling trailers. It has a 350 engine and a 4 barrel carburetor and only gets 10 mpg. Interestingly, while pulling our 23' travel trailer, the van still burned 10 mpg!
Averaging about 16 MPG.
12.8 at the most
My 1989 G20 van gets 15 mpg
bad MPG 8 city 10 or 11 highway
apx-14 city-18 freeway-
14 city 17 hiway
12 mpg
8-16 mpg
My 95 Chevy Astro van averages 15 mpg in the city. I do not know what it gets on the highway. It has a 4.3 L V6.
I get about 14 mpg highway.
!2.6 mpg easy driving
There is no answer to this without more info; Engine size, body type and driving style will all have differing MPG's. For example my van gets 20mpg when I drive, my wife gets 16mpg, same van different driver!