WHY HAVE I commandeered your attention with this strange and irresistible object? It is obviously not a car. It cannot possibly be real. Does it even have wheels? Is it a submarine?

Sixty years after its introduction at the Paris Auto Show, the futuristic, perfectly Gallic Citroën DS 19 (D series from 1955-75) retains the ability to wow, an atom bomb of style from a time when atom bombs were kind of cool. The DS was the most technically gifted automobile of its time and the most quintessentially modern, in that it scorned all that was familiar in prewar design—big, exposed wheels, low roofs, strong shoulders and commanding chrome grilles—in favor of something utterly new, at least outside the realm of pulp science fiction.

And yet until two weeks ago I had never actually driven a DS. Now, thanks to the Lane Motor Museum in Nashville, Tenn., which let me take theirs out of the barn, I must have one. That is a problem because I have neither the time, money nor garage space to devote to a temperamental French car that looks like a glass escargot.

And yet, yes, I can feel it. I’m taking la plongée. And if I can own only One Classic Car—I’m pretty sure that would be my wife Tina’s position—the OCC would have to be the Citroën DS. It’s the ultimate desert-island car, the default choice, the go-to. Anyway, this is my journey to oui.

The DS is not just any old car, as is obvious should you park one next to a ’55 Chevy Bel Air, which then appears to have been built by cave-dwellers. The DS was a front-mid-engine, front-wheel-drive car with rear wheels closer together than at the front, allowing its sleek, tapering bobtail. The rears are enclosed in prim fender spats and, above, the remarkable panoramic greenhouse and fiberglass roof, canted like a beret. Did we mention it was French?