Oh, the untainted optimism of 2014. In the spring of that year, the good Swedes at Volvo introduced Drive Me, a program to get regular Josefs, Frejas, Joeys, and Fayes into autonomous vehicles. By 2017, Volvo executives promised, the company would distribute 100 self-driving SUVs to families in Gothenburg, Sweden. The cars would be able to ferry their passengers through at least 30 miles of local roads, in everyday driving conditions—all on their own. “The technology, which will be called Autopilot, enables the driver to hand over the driving to the vehicle, which takes care of all driving functions,” said Erik Coelingh, a technical lead at Volvo.

Now, in the waning weeks of 2017, Volvo has pushed back its plans. By four years. Automotive News reports the company now plans to put 100 people in self-driving cars by 2021, and “self-driving” might be a stretch. The guinea pigs will start off testing the sort of semi-autonomous features available to anyone willing to pony up for a new Volvo (or Tesla, Cadillac, Nissan, or Mercedes).

“On the journey, some of the questions that we thought were really difficult to answer have been answered much faster than we expected,” Marcus Rothoff, the carmaker’s autonomous driving program director, told the publication. “And in some areas, we are finding that there were more issues to dig into and solve than we expected.” Namely, price. Rothoff said the company was loath to nail down the cost of its sensor set before it knew how it would work, so Volvo couldn’t quite determine what people would pay for the privilege in riding in or owning one. CEO Hakan Samuelsson has said self-driving functionality could add about $10,000 to the sticker price.

Volvo’s retreat is just the latest example of a company cooling on optimistic self-driving car predictions. In 2012, Google CEO Sergey Brin said even normies would have access to autonomous vehicles in fewer than five years—nope. Those who shelled out an extra $3,000 for Tesla’s Enhanced Autopilot are no doubt disappointed by its non-appearance, nearly six months after its due date. New Ford CEO Jim Hackett recently moderated expectations for the automaker’s self-driving service, which his predecessor said in 2016 would be deployed at scale by 2021. “We are going to be in the market with products in that time frame,” he told the San Francisco Chronicle. “But the nature of the romanticism by everybody in the media about how this robot works is overextended right now.”

The scale-backs haven’t dampened the enthusiasm for money-throwing. Venture capital firm CB Insights estimates self-driving car startups—ones building autonomous driving software, driver safety tools, and vehicle-to-vehicle communications, and stockpiling and crunching data while doing it—have sucked in more than $3 billion in funding this year.

To track the evolution of any major technology, research firm Gartner’s “hype cycle” methodology is a handy guide. You start with an “innovation trigger,” the breakthrough, and soon hit the “peak of inflated expectations,” when the money flows and headlines blare.

And then there’s the trough of disillusionment, when things start failing, falling short of expectations, and hoovering up less money than before. This is where the practical challenges and hard realities separate the vaporware from the world-changers. Self-driving, it seems, is entering the trough. Welcome to the hard part.

Technical Difficulties

“Autonomous technology is where computing was in the 60s, meaning that the technology is nascent, it’s not modular, and it is yet to be determined how the different parts will fit together,” says Shahin Farshchi, a partner at the venture capital firm Lux Capital, who once built hybrid electric vehicles for General Motors, and has invested in self-driving startup Zoox, as well as sensor-builder Aeva.)