[bvanderveen]

A random dimensional analysis that I find amusing about fuel consumption units:

liters / 100 km => m^3 / m => m^2

(volume) / (distance) => (area)

This can be interpreted as the cross-sectional area of a hypothetical trough of fuel running alongside the road, whose contents you slurp up and consume in your engine as you pass (in lieu of using fuel stored in an onboard reservoir).

[chrismorgan]

Another really fun one, though slightly less literal than L/100km, is charging rates in electric vehicles, which often present charge state as range (km), rather than energy stored (kWh); and so if it takes you one hour to gain 300km of range, well… you were charging at a rate of 300km/h.

(With in-flight refueling, you could potentially refuel an aeroplane at 300km/h at 300km/h…)

Related: Uncanceled Units <https://xkcd.com/3038/>. (“50 gallons per square foot” especially is similar to your L/100km: volume ÷ area = length.)