Hypermiling is a relatively new term originating in the United States, mainly due to increasing gas prices over the past several years. Hypermiling, in basic terms, is the practice of maximizing fuel economy, or in other words, trying to get the maximum miles per gallon from your car.
The term "Hypermilers" was coined by a man named Wayne Gerdes who is considered to be the father of hypermiling, and actually holds records for most miles per gallon in several types of vehicle.
There are a wide variety of practices that constitue hypermiling, ranging from safe and easy techniques like using cruise control whenever possible, reducing usage of brakes, and coasting whenever possible, to more dangerous and sometimes illegal activities like running red lights and stop signs, and turning off the car's engine and coasting while driving.
Although hypermiling is a fairly new concept, the number of hypermilers hitting the roads is rapidly increasing, mainly due to the serious need for better fuel economy in the United States. A hypermiler can practice their techniques in virtually any kind of vehicle ranging from a fuel efficient hybrid, to a half-ton pickup truck to a sluggish conversion van.