Hello,
In my R65, the most fuel I put in the tank was ... 22 liter. I ran dry on the Autoroute A10 near Saint Chelly D'apcher, at 3 am .... Needless to say the missus was quite unhappy...
I've found on this occasion that Mr BMW measuring was right. They said 22 l and it was 22 l. You have to know that in France and on high speed motorways, gas stations are at least 50 km apart. On this particular region, there where a merge between two companies of motorways. So each of them put the first station 50 km from the limit. Making 100 km between them. And with the RT fairing, riding 2 and the Krauser luggage plus a big bag on the rear, at 130 km/h, I could not make 100 km on reserve....
Since then, I fill her as soon as the reserve come into play.
Here in France, gas is at around 1€50 for 95 E10 (10% Ethanol) per liter, 1€60~65 for 95 E5 (5% ethanol) and around 1€70 for 5% Ethanol 98 octane.