A small electric-vehicle company backed by UPS wants to replace the assembly lines automakers have used for more than a century with something radically different — small factories employing a few hundred workers.

The company, Arrival, is creating highly automated "microfactories" where its delivery vans and buses will be assembled by multi-tasking robots, breaking from the approach pioneered by Henry Ford and used by most of the world's automakers.

The plants would produce tens of thousands of vehicles a year. That's far fewer than traditional auto plants, which require 2,000 or more workers and typically produce hundreds of thousands of vehicles a year.

The advantage, according to Arrival, is that its microfactories will cost about $50 million rather than the $1 billion or more required to build a traditional factory.

The company, which is based in London and is setting up factories in England and the United States, said this method should yield vans that cost a lot less than other electric models and even today's standard, diesel-powered vehicles.

"The assembly-line approach is very capital-intensive, and you have to get to very high production levels to make any margin," said Avinash Rugoobur, Arrival's president and a former General Motors executive. "The microfactory allows us to build vehicles profitably at really any volume."

Manufacturing robots at Arrival, which says it has come up with a cheaper way to build vehicles in small factories. But can it deliver on that promise?

The company hopes its electric vehicles will disrupt the normally sleepy market for delivery vans. Such vehicles are well-suited to electrification because they travel a set number of miles a day and can be charged overnight.

Arrival has already won over UPS, which has about a 4% stake in the company and plans to buy 10,000 Arrival vans over the next several years.

In Arrival's factories, a motorized platform will carry unfinished vehicles among six different robot clusters, with different components added at each stop.

The company is also replacing most steel vehicle parts with components made from advanced composites.

The use of composites, which can be produced in any color, would eliminate three of the most expensive parts of an auto plant — the paint shop, the giant printing presses that stamp out fenders and other parts, and the robots that weld metal parts into larger underbody components. Each typically costs several hundred million dollars.

Arrival, which in March began trading on the Nasdaq exchange, hopes to start producing buses by the end of this year, but its ideas remain unproven. Automating auto plants is notoriously tricky. Tesla blamed overreliance on robots for the troubled start of its Model 3 production line in 2018.

Manufacturing robots are usually programmed to do one or two tasks. Arrival is counting on its robots to handle a variety of jobs.

"For high-volume applications, this doesn't seem workable," said Kristin Dziczek, senior vice president of research at the Center for Automotive Research in Ann Arbor, Mich. "Automation is great for things that are repetitious and precise. But if they are talking about very low volume, it could be viable."

UPS has been working with Arrival almost since the startup's founding, said Luke Wake, vice president of maintenance and engineering in the UPS corporate automotive group.

The shipping giant has helped design a delivery van that affords greater visibility for drivers than a traditional truck and is easy to load and unload.

Wake said he had monitored Arrival's progress closely, visiting the company two or three times a month on average.

While he acknowledged that Arrival's untried approach to producing trucks posed a risk, he said it could accelerate the use of electric vehicles in package delivery.

"Things can change rapidly when all the foundations are in place," he said. "We have invested in Arrival and have worked hand in hand to develop the vehicle."