Hogsheads per furlong works perfectly well, provided that you know what good and bad values are for it. I just use mpg because I still have 40 years of figures in my head for the average fuel consumption of every vehicle since whenever.
I no longer have any idea how much fuel is in the car. The capacity gauge is a titchy wee thing that just shows full / half / empty. But I also have a (trustworthy) display for "miles left". The similar display for mpg has become a shorthand for "is the aircon on?" "Is there a soft tyre?" as the consumption is otherwise so stable. It's not even like there's a road round here where you can go over 50 (60 on a good day).