From an article regarding the first and only civilian owned Harrier:

"He described his airplane as extremely responsive, extremely nimble, and an absolute pleasure to fly. It is a thirsty bird, though, consuming fuel at the rate of a gallon every two seconds while hovering."

Fuel flow measured in gallons per second....wow.

Here's the video of the first performance if you're interested in such things....I've always loved these things.

http://www.airshowbuzz.com/videos/view.php?v=a412fa65