If you want to see the future of car design, you might want to look to the past, to the concept cars designed decades ago.

Take L'Œuf électrique, a three-wheeled, egg-shaped electric model built for personal use by the French artist, industrial designer, and engineer Paul Arzens in 1946. It was conceived as a response to gas shortages during World War II, and it never went into production. But its fuel efficiency and compactness foreshadowed today's Smart cars and hybrids.

L'Oeuf Electrique, 1942; designed and fabricated by Paul ArzensPhotograph by Michel Zumbrunn and Urs SchmidL'Oeuf Electrique, 1942; designed and fabricated by Paul Arzens

L'Œuf is one of 17 such motorized artifacts on display in Atlanta at the High Museum of Art's Dream Cars: Innovative Design, Visionary Ideas, an exhibition of the vehicles that drove consumers' love affair with cars. The exhibition, which just opened, is a deep dive into the history of concept cars, those one-of-a-kind or limited-edition models whose advanced features push the limits of what is possible. These are true "dream cars," plucked from the imaginations of designers, who sculpted their visions from steel, rubber, and engineering know-how for big-name brands like Chrysler, Cadillac, and Ferrari but also forgotten companies such as Tasco and Stout.

Cadillac Convertible Concept Car, 1951Illustration by Carl Renner, collection of Jean S. and Frederic A. SharfCadillac Convertible Concept Car, 1951

Why would manufacturers invest in building cars that they never intended to put into production? As automobile ownership grew in the early 20th century, so did buying preferences that went beyond mere function. The premium on design—different shapes, styles, and colors—dovetailed with the rise of advertising and marketing. Ads from the era, writes show curator Sarah Schleuning, "signified the importance of creating desire and perceived need for objects such as cars, and the development of a significant consumer market."

Scarab, 1936; designed by William B. StoutPhotograph by Michael FurmanScarab, 1936; designed by William B. Stout

Carmakers still use concepts as testing grounds for innovation, but very few present-day prototypes approach the drool-worthy, muscly beauty of these roadsters. Like sci-fi writers from the same era, the designers of these concepts would be sorely disappointed to find that today's cutting-edge car design is a Tesla with gull-wing doors.

Dream Cars is on view until Sept. 7.