A Boeing 747 uses around 36,000 gallons of fuel over the course of a 10 hour flight. “Outrageous” we hear you shout, but let us take a look at the miles per gallon.
Consider that a 747 can carry as many as 568 people, but let us assume that only 500 of the seats on the plane are occupied.
A 747 uses 5 gallons of fuel per mile, so if we divide the number of people by the gallons per mile that gives us 0.01 gallons per person, per mile. In other words the miles per gallon, per person, is 100 miles.
If you compare than to a single person driving a car, the average miles per gallon (combined urban and extra urban) is around 38 miles, almost a third that of the Boeing 747.
When viewed like this is does not seem quite so bad, especially as the plane travels at 550mph!