Gallon
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Definition
A volume unit with two definitions: the US gallon equals 3.785411784 liters; the imperial (UK) gallon equals 4.54609 liters.
Explanation
The US gallon is about 20% smaller than the UK imperial gallon — a critical distinction for fuel economy comparisons. US fuel efficiency is measured in miles per gallon (mpg); a car getting 30 US mpg achieves only about 25 UK mpg. One US gallon = 4 quarts = 8 pints = 128 US fluid ounces. US gas prices per gallon are roughly one-quarter of European per-liter prices before unit conversion.
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