If Rumpler started the trend toward the efficiencies of aerodynamics, then Paul Jaray, a former zeppelin designer, gave it a big push into mainstream auto production with his car, the Tatra Type 77, a car with a blunt, rounded nose that swooped over the cabin and tapered off into a long tail over the rear-mounted engine. The design enhanced "laminar flow," the gradual shifting and increased velocity of air the closer it gets to the surface of a moving object, sometimes referred to as "streamlined" flow.
Beginning in the 1930s, specifically 1932, production car designers were shying away from the square-shaped cars that were built on simple, high-stepped carriage-influenced chassis with foot boards, sunshades on the exterior of the windshields, detached headlights, and rear lights set off of the fenders. They were bulky, awkward, and heavy. From 1932 on American cars changed as well. American cars appeared with rounded edges, headlights built within the chassis of the car, but the driving comfort improved, too. The radiator grille and shell were raked back slightly, which made the cars look speedier. And speed sold just as well then as it does today.
The aerodynamic vision also became an important part in designing cars throughout the '30s. Aerodynamics and the streamlined design increased as well as the volume of the automobile's engine. Streamlining a car also meant that more fuel, which already was cheap in the U.S., could be saved because of this streamlining.
The greatest impact of the streamlined designs was in fact that the car became an eye-catcher. Automobiles came to look like art. The first automobile producer in the U.S. who really used the techniques of aerodynamics and streamlining was Chrysler and its Airflow model in 1934. The Airflow, although a big step in the breakthrough of aerodynamics in America, was poorly received and dropped from the line soon thereafter. The changes made to the design also brought a revolution in body styling. Shortening the hood and moving the passengers forward allowed modern "fastback" lines, with grilled radiators and skirted fenders. Cars like the '36 Lincoln Zephyr set styling patterns for years to come, though these designs only gave the appearance of drag reduction and only a few examples provided results.
In Europe, Auto Union had made considerable progress in the development in the mechanics of its cars, but its engineers were now seeking new methods of styling and material selection for their body development work to increase efficiency and speed.
The Central Body, Development, and Design Office pursued the idea of streamlining from the very outset, using the patents of Paul Jaray as its basis. The optimum aerodynamic properties were first calculated by theoretical methods, then tested out in the wind tunnel. For example, the production version of the DKW F9 achieved an astonishing drag coefficient of 0.42 using this method (the F8 was 0.58, for comparison).
Through the years, countless factors have shaped the way cars are designed, from increased safety regulations to the price of oil. In most of the passenger vehicles we see on the road today, aerodynamics play a comparatively minor role in the overall design of the vehicle. John H. Lienhard, a professor of mechanical engineering and history at the University of Houston and author of The Engines of Our Ingenuity adds, "It took time for engineers to see that they had to smooth the bottom of an automobile as much as the top. It took time to see that sharp corners on the front of a car were terrible drag-inducers. Only in the last generation did 18-wheelers sprout those strange-but-effective, drag-reducing cowls over their cabs." We have come to associate an appealing car design if it emulates the lines of a racecar. Aside from making a car as aerodynamically safe as possible within specific design parameters, other considerations arguably play more prominently into the final production line of most vehicles, and its success doesn't hinge on how quickly it slips through the atmosphere; if it did, we would have never witnessed the boon in SUV sales in the last decade or the minivan rush the decade before. All cars today would be shaped like a drop of rain.
Of course, the downside to better technology and higher demand for drag reduction is that, according to Lienhard, modern cars are "looking more and more alike. As designers work with increasing knowledge of design limitations, they close in on optimal designs that cannot vary much from one car to the next."