Posted this comment last January - see "1200GSA fuel"
"Today I performed the acid test, armed with a can containing about 4 litres of best unleaded in one of the boxes, I ran the tank dry. So now I know! ( on R1200GS not GSA)
After zero on the countdown tripmeter, on fast-ish A & B roads, I can get another 24 miles before the tank is dry.
That equates to well over 2 litres by my reckoning, nearly half a gallon!!!
I think that is worth knowing for when I'm in the back of beyond with a low tank, eh!"
Mind you, I've run out of fuel twice since then, so I don't think the bloody thing is that accurate------
Phil