From systems,

given the shared respect for each company’s mission.”

TALENT POOL

It’s well-known that SpaceX and Tesla share high-level leadership, with several people — Mr. Musk, his brother Kimbal, venture capitalist Steve Jurvetson and Antonio Gracias of Valor Equity Partners — on the boards of both companies. Some of the same bigmoney backers that helped make SpaceX one of the world’s most valuable privately held start-ups have also invested in Tesla, including Fidelity — the car maker’s biggest shareholder after Mr. Musk, who owns about 20%.

The brainpower collaboration also seeps into the ranks. When Tesla announced the hiring of Chris Lattner from Apple, Inc. as vice-president of its Autopilot software division in January — a position he left after only six months — the car maker gave a shout-out to a SpaceX executive who pulled double duty at both companies during the search.

After Lattner left Tesla earlier this summer, the automaker hired Andrej Karpathy as the new head of its Autopilot program. Mr. Karpathy was a research scientist at OpenAI, another Musk enterprise that advocates for the responsible development of artificial intelligence.

MATERIAL LINKS

Both cars and rockets need to stay trim and light to get where they’re going, making material science another key area where the companies can collaborate. And that’s not hard to do, with Charles Kuehmann serving as the vice-president of materials engineering for both companies. He joined Mr. Musk’s empire from Apple in 2015.

The materials teams at both companies sometimes hold joint meetings — in person and via conference call — to brainstorm and discuss materials issues, according to Tesla. SpaceX executives have visited Tesla’s auto assembly plant in Fremont, California, where they can get a hands-on look at higher volume manufacturing. Both companies are headquartered in the Golden State.

Besides the need for advanced materials, Tesla and SpaceX both manage galactic amounts of data, from the millions of miles traveled on Autopilot to the telemetry of rockets. The two companies have codeveloped a computer system that catalogs material specifications and data and feeds it into analytic tools. The data, information and computers that house the systems are unique to each company, but the software was developed jointly, Tesla said.

“As an industrial community — whether it’s aerospace or automotive — everyone is grappling with increasing data management and the search for stronger, lighter, cheaper materials,” Luigi Peluso, an aerospace and defense consultant at AlixPartners, said in an interview. “People who can master those skills can play in either domain pretty fluidly.”

OTHER OVERLAPS

Even the company plane is shared. Tesla paid SpaceX roughly $1.1 million for use of the corporate jet in 2016, company filings show.

SpaceX has also indirectly helped Tesla when it bought some of SolarCity’s bonds. The Musk-linked panel installer sold solar bonds before the merger with Tesla but found few takers outside of Mr. Musk, his cousins Lyndon and Peter Rive and SpaceX.

Other connections between the company are more cultural.

“It’s not unusual to see people at Tesla gathered around their computers to cheer on SpaceX launches, and lots of SpaceX employees drive Teslas,” a spokesperson for the automaker said in an e-mailed statement.

FUTURE COLLABORATIONS

For now, the two most-watched companies in Mr. Musk’s empire focus most of their collaboration on tangibles like software, engineering, materials and expertise managing a vast network of suppliers.

Longer term, analysts like Morgan Stanley’s Adam Jonas can’t help but wonder if a company that ultimately plans to build and launch its own satellites might have a leg up in the race for driverless cars, which will have to be connected to a vast wireless network. A colleague of Jonas raised the issue on a 2016 conference call. It’s an edge that other car makers like General Motors Co. and Toyota Motor Corp. won’t have.

Mr. Musk has so far been mum on how SpaceX could help Tesla’s driverless dream, but that’s not stopping analysts from seeing synergies.

“Elon has a lot of irons in the fire, and SpaceX is his number one baby,” said Ben Kallo, an analyst with Robert W. Baird. “SpaceX can contribute to what Tesla is doing. There’s a lot of crossover, and it gives Tesla a complete advantage over other automakers.” — Bloomberg