The “bone line” is what automotive designers refer to when talking about the hard, almost sharp line that runs across the profile of most modern cars, and should not to be confused with the “belt line,” which is represented by the junction of the upper glass area and lower bodywork – the so-called shoulder line.
In the randomly selected case of the 2014 Audi A8/S8, you can see the bone line running from low on the front bumper (lip), then continuing along the side through the middle of the fuel filler cap door, greatly emphasizing the slightly tapered profile, especially when viewed from the very common front three-quarter perspective.
This distinction was made clear(er) via examples in a new video on automotive design uploaded by Autoline Daily. It goes into when and how this design feature gained popularity, and which cars it was first used on. The idea was that it wasn’t possible to get the effect on cars that had separate wheel pods (like on most 1930s and 1940s vehicles), so it was only from the late 40s onward that it began gaining ground.
When it comes to modern cars, the great majority have clearly defined bone and shoulder lines that set the tone for the proportions and the basic body shape. However, only ones that are truly designed to stand out tend to accentuate these two lines purely to attract attention by making the body look chiseled and aggressive (both desirable traits on the showroom floor).
By Andrei Nedelea