The best way to derive operational efficiencies can be learnt from the aviation industry. Recently United Airlines flew an airliner from Chicago to Frankfurt and ended up saving 1,400 gallons of aviation fuel (that's approximately 5,600 litres). See what the wired story says:

The flight, made earlier this month, and was a regularly scheduled trip but United and its partners, including air-traffic controllers in the United States, Canada and Europe, had been planning it for some time. Several fuel-saving techniques were used, but the main goal was demonstrating how a flexible flight path allows pilots to take advantage of favorable winds, says Joe Burns, director of flight tests at United.