Burn and coast
Burn and coast is also known as pulse and glide. This method consists of accelerating to a given speed (the "burn" or "pulse"), followed by a period of coasting (or "gliding") down to a lower speed, at which point the "burn" is reiterated. Coasting is most efficient when the engine is not running, although some gains can be realized with the engine on (to maintain power to brakes, steering and accessories) and the vehicle in neutral, or even with the vehicle remaining in gear. If a manual transmission vehicle coasts with the engine off, it is typically re-started by popping the clutch. The engine control units of some vehicles command a richer fuel setting immediately after the starter is activated, so the bump-start manual transmission vehicle will typically achieve the best fuel economy gains.[16]

Some hybrid vehicles are well-suited to performing the burn and coast. In a series-parallel hybrid (see Hybrid vehicle drivetrain), the internal combustion engine and charging system can be shut off for the glide by simply manipulating the accelerator.

For coasting in gear, a later-model vehicle with a fuel-injected engine will realize more gains from the burn and coast technique than older carbureted engines because the engine control units in most fuel-injected engines will cut fuel to the engine when the car is in gear, the throttle is closed and the engine is running faster than idle speed. This is sometimes referred to as "deceleration fuel cut off". This will often engage while a car is coasting down a hill and is common in both automatic and manual transmission vehicles, although the particular engine speeds at which it will engage vary.

http://en.wikipedia.org/wiki/Fuel_economy-maximizing_behaviors