I find this discussion of what you can get out of the battery very interesting.
I usually charge my car to 90% and then potter about the Isle of Wight. Invariably I find that I can drive more than 60 miles as the battery level drops to 70% - using up 20% of the battery, even in the cold(er) weather, (today being a good example), which gives a "whole battery" figure in excess of 300 miles (30+ miles driven on 10% of the battery). However, carrying on, the consumption increases, so that when the battery gets down to 50% (having used 40%) the distance driven is in the order of 110 miles. This works out at about 27 to 28 miles to 10% of battery (110 miles divided by 4), or 270ish miles to a "full tank". When the battery level falls below 50% consumption increases even more and the "whole battery" figure drops to 250 miles or so.
I have considered recharging - I can do it at home - every other day or so, to stay in the 300+ mile zone, but I am not sure whether this would have a long-term detrimental effect on the battery. I drive only a dozen or so times on the mainland each year, distance anything up to 200 miles or more, for which I always charge to 100% before I set off, and usually get about 260 to 280 miles to a full charge equivalent, especially if I am carrying more passengers than my usual me plus one.
Overall, I am happy with these consumption figures, but I am sure that a lot of the good local figures are due to where I live. There are few roads where it is safe (and legal) to drive faster than 40 to 50 mph. The majority of my driving is within a 10 mile radius from home, which I think accounts for much of what I find.