In 2016, nobody knew what Argo AI was.

It was a scrappy artificial intelligence startup with lofty goals and industry veterans ready to jump ship from other self-driving firms, eager to try a new approach of making robot cars.

Reinventing the wheel was not exactly on CEO Bryan Salesky’s agenda.

The heart of Argo’s business model was — and is — quintessentially anti-Silicon Valley: Snuggle up with industry titans that have deep pockets and make them investor-partners. To this day, the startup has funding from only two firms, keeping the rest of the equity for employees.

“We always thought that would be a compelling business model because it’s a capital-intensive thing,” said Mr. Salesky, a Pittsburgh native. “That’s not foreign to a large manufacturing company. They need the help because those companies don’t typically build software well.”

Truth is, no company trying to crack the autonomous vehicle code is moving anywhere quickly without help. A complicated web of partnerships and acquisitions has formed, helping firms create economies of scale to become more efficient.

Even companies working together to leverage one another’s expertise haven’t dropped their guard. Mr. Salesky believes that when the winning self-driving companies do emerge, he’ll be able to count them on one hand.

But it’s still worth partnering up. Companies that work together will find success more quickly than larger firms keeping to themselves, if the parties can put ego aside, he said.

Three years after its founding, Argo has wooed two of the industry’s major auto manufacturers, Ford and Volkswagen, into investing billions of dollars into the business, which hit a $7 billion valuation in mid-July.

“Automobile companies realize that if they don’t partner, they’ll be left behind,” said Timothy Derdenger, associate professor of marketing and strategy at Carnegie Mellon University’s Tepper School of Business in Oakland.

“They don’t have the technical capabilities to really go alone at it, or if they did have the technical capabilities, they’re so bogged down by the slow pace of their industry.”

Winners and losers