Reply #5: Don't the Brits use the "Imperial gallon?" [View All]

[Sal Minella]

Imperial (UK) gallon is legally defined as 4.54609 litres (~277.42 cu in), which is about 1.2 U.S. liquid gallons. This definition is used in the United Kingdom, and is based on the volume of 10 pounds of water at 62 °F. (A U.S. liquid gallon weighs about 8.33 pounds at the same temperature.) The Imperial fluid ounce is defined as 1/160 of an Imperial gallon. The Imperial gallon is no longer legal, in the UK, for trade or public administration purposes, but it is used colloquially (and in advertising) for fuel consumption figures in miles per gallon. The Imperial gallon continues to be used as a unit of measure for fuel in various countries (for example, United Arab Emirates and Sierra Leone).

http://encyclopedia.thefreedictionary.com/imperial+gallon