You're in the middle of nowhere, you've left your car with the headlights on, and come back to find that when you turn the ignition key, you get a click and nothing else. Your battery is flat. And you've got nobody else nearby with another car, who could give you a Jump Start.
Let's push-start your car.
We'll assume a few things first though.
- There are at least two of you, preferably three or four. Cars are heavy things to push, and one of you needs to sit in the car. Or you're on a steep downwards hill with no other cars around.
- There's no other cars around, or no jump leads to jump start the car. As that's easier than push-starting it. See How to Jump Start a car.
- You're in a car with a manual transmission (stick shift). Push-starting automatic cars is very difficult, if not impossible.
So, here's what you do.
- One of you sit in the drivers seat.
- Turn off all auxilliary things (headlights, radio etc).
- Turn the key to "run".
- Put the car into 2nd gear (if there's a slight slope or a lot of people pushing), or 1st gear (if you won't be able to get up much speed).
- Put your foot on the clutch.
- Take off the parking brake (handbrake).
At this point, everybody else should start pushing - or if you're on a hill, let yourself roll down the hill, so you pick up speed. Make sure you keep yourself pointing in a sensible direction!
When you reach a reasonable speed (which can be as low as 5 mph for 1st gear), very quickly release the clutch and then push it in again, and then put your foot on the accelerator.
Releasing the clutch links the wheels (which are moving) to the engine, doing the same job as the starter motor does. In theory, the engine should jerk into life with a "bump" (hence the alternative name for the process, bump-starting).
Pull in somewhere safe and rev the engine for a couple of minutes to put some charge back into the battery. If you stall it immediately, you may need to repeat the process as it may not have built up enough charge to run the main starter motor yet.
If you've got an automatic car, you can theoretically do this. Put the key to "run" and the gear selector in neutral. Get the car up to about 30 mph (hence why it's not easy!) and then flick it into "Drive". May or may not work.
OK, as Miles_Dirac points out, you can theoretically push-start a car on your own, with the driver's door open and pushing with your feet. But it's even harder and more dangerous (as you have less control). Don't do it!
unperson mentioned that the "run" position on the ignition is sometimes labelled "on". He also said that he's heard the quick up-down movement on the clutch called "popping the clutch".
xq says "There is no need for it to be pointed downhill. It works just as well in reverse, and more exciting too." Yes, he's correct. Please. For the love of G-D, don't push-start your car in reverse!!!!!