Sketching a car is all about adding layers, gently adding more detail. The biggest challenge is always to stop sketching: sometimes a sketch is nicer when you apply the “less is more” principle. At this stage, the headlamp is now ellipse. I’ve added the lower air intake and the bottom of the door is starting to show more shape. Note the air outlet in the lower area of the bumper and the detail on the rear fender. I’m trying to create a feeling of a strong rear shoulder. There’s a very fine line between the wheels now,  just below the belt line. It’s very fine and doesn’t exist in the previous image. This very fine line gives the side – the surface between the wheels – a more three dimensional feel. It’s not an accident that this very fine line, when it comes closer to the rear wheel, is dropping. It doesn’t mean that on the final product the line drops, it’s just a way of visualising and giving the person that’s looking at the side view an impression of how the car might look in the flesh. If you look at the 911 from above, the rear track of the car is a little wider and these fainter lines help to indicate this.