What would you do if your car plunged into a body of water?

If you're like super-spy Sydney Bristow on ABC's "Alias," you really don't need to worry. After all, you're trained for this kind of thing...and you're a genius.

But what about us normal folk? Since watching a recent nail-bitingly intense episode of "Alias" where our favorite spy is stuck in a sinking vehicle, we wondered what average drivers like us should do to escape such a situation.

First things first: pop your seatbelt. You'd be surprised how many people end up dying because they panic...and forget that they're still buckled in.

Next, roll down the windows immediately. An open side window is your first means of escape. This is when those of us with manual roll-down windows are thanking our lucky stars -- if you've got automatic windows, you must act fast. In most cars with automatic windows, the motor that powers the window is located halfway up the car door. Once water hits it, you won't be able to roll down your windows and will have to find another means of escape.

Don't even think about trying to open the doors. Once the bottom of your door is even slightly submerged, the water pressure makes it almost impossible to open the door until the car is nearly full, which equalizes the pressure. If you want to escape by your car door, you'll have to wait until the car is completely underwater (see below).

It takes a car anywhere from two minutes to almost ten to sink. But beware that there’s a good chance your car may flip upside-down as it sinks. Try to hang on to something (like the steering wheel) so you can orient yourself as soon as possible.

If you haven't been able open a window, you're going to need to break one in order to make your escape. Brace yourself across the front seat and slam your heels into the driver's side window. Or if you're one of the few who have a center punch in your glovebox, use it to break the window. (A center punch, available hardware stores, can shatter windows. Simply place the point firmly against the window and push.)

If you can't break the window or aren't strong enough to, your very last resort is the car door (provided it is unlocked). You must wait until the water inside the car equalizes the pressure of the outside water. This means that you must take a generous last breath, open the door underwater, then swim to the surface. One common mistake is losing your sense of direction in the water. Follow the direction of the bubbles or where your body naturally wants to float.

You might not be as brawny as Sydney Bristow, spy extraoridnaire, but armed with the aforementioned tips, you'll be able to survive a sinking vehicle. Undercover operations are an entirely different story.