Beyond the technical aspects of headlights for automobiles there is the consideration of the various ways these are arranged in a car for appearance's sake. The greatest variety is of course found in the headlights specially designed for a particular automobile, and which can be of any shape, but the cheaper, standardized sealed-beam headlights had limited options for what they could add or detract from the looks of the front of a car.
The arrival of five-inch (~125 mm) sealed beam headlights brought a few possibilities. Designs that remained in the studios of the major American automobile firms actually tried to put two of these lights on or near the centerline of the car, either side by side or one above the other. This was, however, banned by the federal government. Most cars had their headlights in pairs side by side on each side of the car; some models of Oldsmobile had a parking light in the middle of the pair.
The next best arrangement was one above another at the extreme ends of the car. Pontiac, American Motors, and then Cadillac had great success with this design. The models of Mercedes-Benz sold in America adopted this arrangement because their special lights were banned. The British firm Alvis and the French firm FACEL also used this for some of their cars.
The worst arrangement was to have the headlights undeniably diagonally placed. This pattern had the top lights at the outside ends of the car and those below set in so as to be at about a 45-degree angle. If anything could be said to be bad luck in car designs, this was it. The 1958 Lincoln and 1959 Buick were sales disasters. Chrysler also used this arrangement to little success.
However, in Britain there developed the notion of having the headlights only slightly diagonal, with the inner ones just a little lower than the outside ones. This was apparently a cue to drivers ahead that the car behind them was fast, so they should get out of the way, as only the fastest of British cars used this arrangement. The Gordon-Keeble was the fastest British car of 1965; the Triumph Vitesse was the fastest Triumph of that year as well. The Bentley Continental of that year also used this arrangement. (source: World Car Catalog)
When standardized rectangular headlights became permitted by the U.S. Department of Transportation, these too were placed in pairs at the edges of the car, side by side. It took Chevrolet to put them one above the other.