In England you pay for petrol (gasoline) by the 'litre' and pricing placards are indicated in p/L (pence per litre).  You measure your fuel efficiency in MPG (Miles per Imperial Gallon).    In the first screenshot below you will notice that an imperial gallon has quite a bit more BTU energy per gallon than a US gallon.  This is because an imperial gallon is equal to 1.2009505 gallons-US.  Another way to look a this is 1 gallon US = 3.7854118 litres (liters) & 1 imperial gallon = 4.546092 litres or liters.  In the second screenshot you see the energy use breakdown that shows fuel usage in British pounds rather than $ dollars.



Below is the Input showing Temps in C, Elevation or Altitude in metres (meters), Load in kg & barometric pressure in millibars.



Below, find screenshots with US values that are almost exactly equivalent to the above UK screenshot values.  You will see some differences in the TRR, RRR & AC-Misc areas.  These are due mainly to tire diameter, different emission requirements & operational processes.  Really, these differences are negligible but, I mention them as some folks will surely be comparing.   18.8 kW for UK vs. 18.96 kW for US is less than 1% difference.