The dream began in 1955, with a tiny, toylike creation called the "Sunmobile." Built from balsa wood and hobby shop tires, it was just 15 inches long. The 12 selenium solar cells that decorated its exterior produced less horsepower than an actual horse. But it was proof of a concept: Sunlight alone can make a vehicle run.

The years went on, and the dream evolved into a converted vintage buggy with solar panels on its roof. Then a glorified bicycle, a retiree's garage project, a racecar that crossed the Mojave Desert at 51 miles per hour.

It is a dream of perpetual motion. Of travel that doesn't do damage to the planet. Of journeys that last as long as the sun shines.

There are problems with this dream, big ones. Clouds come. Night falls. The laws of physics limit how efficiently solar panels can turn light into energy.

But one start-up claims it has overcome those problems. Now, its founders say, the dream can be yours for as little as $25,900.

Aptera Motors, a California company whose name comes from the ancient Greek for "wingless," is rolling out the first mass-produced solar car this year. It's a three-wheel, ultra-aerodynamic electric vehicle covered in 34 square feet of solar cells. The car is so efficient that, on a clear day, those cells alone could provide enough energy to drive about 40 miles — more than twice the distance of the average American's commute.

The Aptera must undergo safety tests before the company can begin distribution, which it hopes to do by the end of this year. Even then, it's not clear that consumers will want to buy something that looks like a cross between the Batmobile and a beetle. The shadow of an initial attempt, which ended in bankruptcy, hangs over the founders as they gear up to launch their new product.

But the Aptera's creators, Chris Anthony and Steve Fambro, think the world needs a car like theirs. Transportation is the largest source of planet-warming pollution in the United States. The Biden administration has made it a priority to reduce vehicle emissions, and several major automakers have pledged to phase out cars and light trucks with internal combustion engines.

After years of dreaming, maybe the time for driving on sunshine is finally here.

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Anthony and Fambro didn't set out to build a vehicle that could run on solar power. They just wanted to make a more efficient car.

Burning gasoline, it turns out, is not a very efficient way to travel; as much as four-fifths of the energy produced by an internal combustion engine is lost as heat, wasted overcoming wind resistance or used up by fuel pumps and other components, according to Energy Department data.

All-electric vehicles perform much better, but they're still not perfect. About 10 percent of the energy that goes into them is lost converting alternating current from the electrical grid into direct current for the battery. Inefficiencies in the drive system eat up another 20%, and the car must still deal with wind resistance and friction, through regenerative braking systems can reduce some waste.

From top to wheels, the Aptera is designed to eliminate as much waste as possible. Its creators say the car is 13 times more efficient than a gas-powered pickup truck and four times more efficient than the average electric vehicle. At least 90% of the power produced by the Aptera's solar panels goes toward making the vehicle move, the company says.

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The Aptera can be recharged the same way a standard electric vehicle is fueled — by simply plugging it into an outlet. Its extreme efficiency means the car can go 150 miles after just 15 minutes at an ordinary charging station.

But an average electric car would need a solar panel "the size of a semi truck" to go farther than a few miles, Fambro said. Meanwhile, a relatively small number of solar cells can propel the Aptera.

"It only works if you have a super-efficient vehicle," Fambro said. But once he and Anthony realized how far the sun alone could take them, "there was no other plan than to make it a solar vehicle."

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When the first solar vehicle, the tiny Sunmobile, debuted at a General Motors trade show 65 years ago, even its inventors were skeptical about its prospects. GM officials told the magazine Popular Mechanics their creation was of "no practical application to the automotive industry at present."

But that challenge was exactly what appealed to Danish adventurer Hans Tholstrup. Feeling guilty for his fossil-fuel guzzling exploits — flying around the world, driving a speedboat around Australia — he wanted to do something to benefit the planet.

In 1982, Tholstrup and racecar driver Larry Perkins unveiled "the Quiet Achiever" — a boat-shaped, single-driver construction topped by a 90-square-foot solar array. A tiller served as the steering system, and the wheels and brakes were borrowed from a bicycle. Eating orange slices to stay hydrated and camping by the side of the road, they took 20 days to drive 2,560 miles across the Australian continent. Their average speed was 15 miles per hour.

Tom Snooks, the project's coordinator, recalled Tholstrup comparing the journey to the flight of the Kittyhawk: impractical but inspirational, and a sign of advances to come. "If it will motivate just one more idea and thought in the development of solar power," Tholstrup said, "then the venture will have been well worthwhile."

In 1987, Tholstrup launched the "World Solar Challenge" to encourage others to improve upon his record. Soon solar races were springing up around the globe, attracting competition from car manufacturers and high school students alike. The vehicles evolved from Tholstrup's "bathtub on wheels" to bullet shapes to three-wheeled cars with curved, winglike solar arrays. By 2013 the World Solar Challenge introduced a "cruiser class" competition in an effort to spur development of more commercially viable vehicles.

"It makes for a really fun design challenge," said University of Michigan mechanical engineer Neil Dasgupta, faculty adviser to the school's highly decorated solar car team. "And we've made tremendous advances."

The team's 2017 vehicle, which placed second in the World Solar Challenge, weighed just 420 pounds and averaged almost 50 miles per hour.

Solar cars have to be small and sleek, Dasgupta explained, because of inefficiencies in solar panels. Photovoltaic cells are limited in what wavelengths they can turn into electricity. They don't perform well when they get hot. Even the best solar panels only convert about 23% of the sunlight that hits them into energy. You can get much more power more quickly by simply plugging into a charging station.

Total reliance on solar power also poses practical problems. It means the car can't be parked in a garage or under a tree. Once the battery is full, any additional energy that hits the solar panels is lost.

"This is a niche kind of thing," said Timothy Lipman, co-director of the Transportation Sustainability Research Center at the University of California at Berkeley. The Aptera, which seats two, wouldn't work for a large family, a commuter in cloudy Seattle, a plumber who has to lug around equipment.

Advances in solar cars could benefit the broader automotive industry, Lipman said. They might lead to the development of lighter materials and make the case for greater efficiency in electric vehicles. Manufacturers could add solar panels to augment car batteries. Maybe the technology will find use at national parks and remote military installations.

But Lipman thinks it will be difficult for sun-powered vehicles to find broad commercial success. A Chinese manufacturer was still seeking funding to produce its prototype when it ran into financial problems last year. The Dutch champions of the first "cruiser class" race in the World Solar Challenge launched their own start-up, Lightyear One, and aim to start deliveries of their large, four-wheel hatchback at the end of this year. Still, the Lightyear car's price tag, about $180,000, puts it out of reach of most buyers.

Anthony and Fambro know how easy it is to fail. Four years after founding Aptera in 2006, they left the venture amid disagreement with other leadership — auto industry veterans who wanted to build a traditional four-wheeled vehicle to qualify for federal loans. But the money never materialized. The company was liquidated in 2011, and its intellectual property sold.

Business analysts treated the collapse as a case study in the perils of launching an automotive start-up. Cars are more expensive to make than software. Federal regulations are difficult to navigate. Consumers are wary of change.

But Aptera's inventors took a different lesson from that experience: "The traditional design process doesn't allow for breakthroughs," Fambro said. "Because anything that's a breakthrough is seen as something that's polarizing, and they don't allow polarizing things to exit the research clinic."

If the Aptera was going to succeed, they decided, they couldn't make compromises to satisfy a federal requirement or a market-research firm's recommendation. They had to be willing to be different.

"That's the march of technology," Anthony said, before paraphrasing Apple founder Steve Jobs. "People don't know what they need until you show it to them."

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After a decade spent pursuing other ventures, Aptera's creators bought back the company in 2019 and launched a crowdfunding campaign to restart development.

Their timing was good. Electric batteries had gotten much cheaper and lighter. Solar cells had become more efficient. Advances in computing enabled the inventors to simulate the vehicles on their desktops, speeding up the design process. Even the constraints imposed by the coronavirus pandemic spurred creativity, Anthony said.

When Aptera began taking preorders last December, it sold out of its planned first batch of 330 vehicles in 24 hours. Almost 7,500 people have now put down deposits for a car.

One of them was Tyler Perkins, the 27-year-old assistant manager of a small airport in Oklahoma City. A technology buff who had been following the company since he was a teenager, he said he was drawn to the Aptera's "funky, radical design" and wanted to make a hopeful bet on tomorrow.

"They're actually like, 'let's build a futuristic car, because if we don't do it no one will,' " Perkins said. "And that's how the future happens."

Concern about climate change already motivated Perkins to become a vegan and drive a hybrid. He wanted to switch to an electric vehicle, but his apartment building offers no charging station. Then the Aptera came on the market. Even without federal tax credits (which only go to four-wheeled electric vehicles) it costs almost $10,000 less than other EVs. Sure it's small, but all he needs is space for himself and his camping gear.

"I think it will work great for me," Perkins said, "as someone who is trying to be as efficient as possible and have a minimal impact on the environment."

Not every Aptera fan fits the stereotype of an avid environmentalist. Nick Field, a 36-year-old accountant in London, is drawn more to the car's long range and high performance; it can go from 0 to 60 mph in 3.5 seconds and hit top speeds of 110 mph. As far as he's concerned, the Aptera's low climate impact is just a fringe benefit.

"I'm in the category of, 'I want to enjoy my life,' " Field said. "I just like fast cars. . . . I think it's really cool."

Anthony acknowledged that the Aptera is not for everyone. But it has more appeal than its skeptics give it credit for, he said. The car's high efficiency means it puts less demand on the grid than ordinary electric vehicles. It could be ideal for delivery trucks and Postal Service vehicles, which don't travel far and spend lots of time idling. Outdoor enthusiasts will probably like the option to venture far from charging infrastructure without worrying about fuel. And the notion of parking an Aptera in the sun and returning to a car that has more fuel than when you left it — free, clean fuel — is a powerful idea at a time when the world is looking for transformation.

"We see solar as the main driver of our business," Anthony said. "It enables so many things."

He considered the dreamers who first conceived of solar cars: Tholstrup subsisting on orange slices during his cross-continent journey, engineering students building racecars after school. He thought about the early developers of electric vehicles, who had faith in a future that didn't run on gas. He remembered the investors who shied away from the Aptera's first incarnation, saying "who is going to buy your weird egg-shaped creation?"

"It's the same thing with anybody who does anything first," Anthony said. "It's always: Why would you do that?"

When Aptera hits the road, he'll have his answer.