here is an off-the-cuff conceptual sketch of a car to show how 2-point perspective works:
between the first sketch and this one, those who don't get it should begin to get it.
you basically choose two points on a horizon line, and project rays, like spokes on a wheel, outwards, towards the rays of the opposite point. you can construct simple cubes this way; within the cubes, you can lay elipses in there.
it is easier to just see it than explain it, so just look at the sketches. it is important to understand recession into space for any flat photograph to make sense. people who do not understand basic perspective constantly mess up elipses, and even the body of the car, as it recedes into the distance.