You'll need to add the camera as a child of the car (drag the camera onto the car in the hierarchy). Take a look at the video from 7:25 to see how this is done. Either that or add a camera follow script, but adding the camera as a child is the quickest way of having the camera track the vehicle.
Move the "Main Camera" under the file of the car. This makes it a "child" of the vehicle which will make the camera move with it.