Most vehicles fuel gauge is not accurate int the top 1/2 anyways so it doesn't bother me much.
Couple of my riding buddies are always anxious to fill up after 200 km so when I ride with them my gauge often still shows 1/2 tank.
I think my average is in the low to mid 50's as well mpg US (just over 5 l / 100 km)
So I guess in theory I could easily do 200 miles per tank.
(all this miles / km / gallon / liter is confusing me lol)