We start sketching simple light lines and wheels to get the good proportioned solid and wheels putting also a light outline for the shadow on the ground.
Now we conentrate on a real car shape outline adding: wheels details, body reflextions lines, glass reflexions, clean up and reinforce shadow on the ground and all lines giving depth (line quality)
This is our final step, we add the shading using the cross hutching technique (crossing lines), we add more details and also transparent feel to the glass area, we work on some cut lines (doors) to give depth and make the sketch more real. Last thing a simple background outline on a vertical position to contrast the horizontal car position (so background pushing the car sketch).
Remeber this is not a design proposal but just a very simple and quick side view tutorial for you!