It is technically possible to push start some automatic cars, but doing so is generally impractical. The car must be pushed to a much greater speed than those with manual transmissions. In addition, their complex transmission systems are not designed for push starts.
If pushed to an appropriate speed, usually between 25 and 40 miles per hour, some automatic cars will start up. Doing so, however, is generally impractical as the vehicle must be pushed with another vehicle and will be difficult to control. In addition, automatic gearboxes are far more complex than manual gearboxes, and this complexity makes them difficult to predict. Attempting to push start an automatic car might cause unanticipated damage.
Manual transmissions, on the other hand, are generally fairly simple to push start. By turning on the ignition, pushing the car to an appropriate speed and releasing the clutch with the stick in gear, the momentum alone is enough to get the engine turning. However, it is important to be safe while doing so.
The Car Connection recommends putting the car in second gear when performing a push start. Second gear is able to handle a wider range of speed than first gear, and the process is usually a bit smoother. It is also possible to push start a car using the reverse gear.