The most common way to push start a car is to put the transmission in neutral, switching the ignition on, and pushing the car until it is at a speed of around 10 km/h (6 mph) or more. This can be done by one person if they are strong enough and/or the car is light enough; a heavier car may require two people. When the car is at speed, one person jumps into the driver's seat (or sits there while the car is being pushed), quickly clutches out, engages second gear, and clutches in. By pushing the car, the wheels make the gearbox rotate, and by engaging a gear and clutching in, contact is made between the wheels and the engine, which may make the engine start by the power of the turning wheels. As soon as the engine can be felt and heard starting, it is advisable to again clutch out to prevent the engine stalling. A too low rolling speed may result in the engine not being able to start.
If the vehicle's battery is severely discharged, the push starting technique can be unsuccessful. The reason is that most modern vehicles are equipped with an alternator without permanent magnets, but rather electromagnets to provide its magnetic field. When starting in a normal way, a little bit of current from the battery is used to provide the initial magnetic field; afterwards, when the engine is running, the alternator can provide its own field current. But when the battery is exhausted, the initial field current cannot be supplied, leading to a 'catch-22' situation. In such a case, recharging the battery or attempting a jump start is a better option.