Originally Posted by Kaldaien

That key's useful for more than just locking the glovebox. Obviously if the key fob has no power or if the car itself has no power the key can be used to lock/unlock the doors, but the only thing I ever use it for is to rollup my windows from outside the car.

Lock the driver's side door using the key and hold it for ~5 seconds and it'll roll up the windows on both sides. It's basically the opposite of holding the unlock button on the fob for 5 seconds to roll them down.