I think the reason why nothing happens when you press the C key is because you haven't changed your orientation yet for that camera view.
Camera view #1: first person driver's view, which is defined in the script
Camera view #2: Camera assumes whatever position you give it in absolute coordinates. I think this is what you want. After spawning your vehicle, press C once, then scroll away with the mouse and scroll wheel. Whatever view you create is the new #2 camera position. In this view the world keeps its position, and the vehicle moves around in a stable world. So Camera 2 could be located wherever you want it as a plane flies past.
Camera view #3: This is like camera view #2, except instead of the camera maintaining an absolute origin in the world, the camera follows the vehicle. In other words, the vehicle stays oriented the same way, and the world revolves around it (like the car avatar on a GPS screen). Positioning camera #3 behind and above a vehicle is a good way to steer effectively.
Once you have established each of the 3 camera views, you can toggle between them by pressing C
You can also change the camera view with the scroll wheel and mouse in Camera view 2 or 3. In order to change camera view #1 you have to edit the script.