Cars of the future--especially those from the past--always exert a powerful pull on our imaginations.
They range from the outlandish (no wheels) to the bizarre (extreme styling exercises) to the jaw-dropping (powered by tiny nuclear powerplants).
While the Fifties and Sixties may have been the height of extravagant future fantasies, the Seventies had its own crop of futuristic ideas.
In 1973, photographer Frank Lodge attended the First Symposium on Low Pollution Power Systems Development, held in October in Ann Arbor, Michigan.
The focus of the conference was on technologies that could reduce vehicle emissions; in fact, the first catalytic converters would arrive the next year.
But the event took place the very same month that the Organization of the Petroleum Exporting Countries (OPEC) announced that it would raise oil prices 70 percent.
That set off the 1973 Arab Oil Crisis, in which the price of a gallon of gasoline suddenly soared, the word OPEC became ubiquitous in daily news reports, and drivers realized for the first time that gasoline was not an unlimited and all-but-free resource.
Conference exhibits and displays were split among the lobby of the Marriott Motor Inn, where the conference was held, and the parking lot of the nearby Environmental Protection Agency testing lab--an outpost of an agency not even three years old then.
Among the displays were a handful of newly introduced battery electric cars, all of them powered by then state-of-the-art lead-acid batteries.
Among them was a striking red ESB Sundancer experimental electric vehicle, which has a long and interesting history of its own.
Lodge's photos are now available for viewing on the Flickr site of the U.S. National Archives.
It's worth browsing through them, to see what advanced vehicle technologies looked like fully 40 years ago.
If you're intrigued by past futures, we also encourage you to read the detailed histories from Hemmings Motor News linked above.
What did the 1973 electric-car futurists get right? And what did they miss entirely?
Leave us your thoughts and your reactions in the Comments below.