Double-clutching is a shifting technique in which the driver releases the clutch as he shifts into neutral, presses on the gas pedal to match the engine's speed to the transmission, then presses the clutch and shifts to the next gear. This maintains smooth power delivery without upsetting the car's balance.
Double-clutching used to be required on older cars in order to ensure that the teeth on the gears meshed properly during a gear change before power was applied. With the creation of the synchromesh transmission in modern cars, double-clutching is no longer necessary, as the transmission synchronizes the speed of the gears before engaging them. As of 2014, performance drivers still employ double-clutching while racing, as the rougher gear changes that occur during normal shifting can cause a car cornering at speeds of over 100 mph to lose its balance and its control.