In Europe fuel consumption of automobiles is measured in litres/100 km.[br][br]Litres are a measure of VOLUME; Kilometers are a measure of length.[br]Therefore, litres/100 km is a measure of AREA.[br][br]In the US fuel consumption of vehicles is measured in miles/gallon.[br][br]Gallons are a measure of VOLUME; Miles are a measure of length.[br]Therefore, miles/gallon is a measure of 1/AREA.[br][br]What is the significance of this AREA?