Final Update: I pulled onto the station forecourt after the engine had begun stuttering (or was that my imagination?) with 211.1 miles on the odometer and it took 12.11 litres to brim it on the centre stand. So, 0.39l left in the tank ish! Indicates I could have cracked the 220 mark, maybe, but that was close enough for my nerves. I now know that a 200 mile range is a workable assumption and my experiments on determining absolute range are hereby ended. It's been informative though.
Ran out of gas one time, only. ( I was just getting used to a VW that had lousy gas mileage - like 14-16mpg sometimes)
New 1980 Vanagon. Slow lane 1-70.
Exit ramp right there, in front of me!
Took it out of gear and coasted, and there was a Shell station at the bottom of the ramp!
Rolled in there in Stealth Mode!
Stig