General Motors said Thursday it has reached an agreement with Tesla to allow GM electric vehicles to charge at 12,000 Tesla Superchargers starting next spring.

GM also will build Tesla’s preferred North American Charging Standard connectors into its EVs starting in 2025, the automaker said. GM will weave Tesla’s Supercharger network into its own vehicle and mobile apps.

“In order to drive EV adoption, we need to have a robust charging infrastructure. And so I’m really excited to announce our collaboration with you and with Tesla,” GM CEO Mary Barra said Thursday afternoon in a Twitter Spaces conversation with Tesla CEO Elon Musk.

“We have a real opportunity here to really drive this to be the unified standard for North America, which I think will even enable more mass adoption,” Barra said.

Barra said Thursday in an interview on CNBC that the automaker expects to save as much as $400 million by working with Tesla’s Supercharger network. GM has said it would invest $750 million on charging infrastructure in the U.S. and Canada.

“This arrangement alone, this collaboration that we’re doing, nearly doubles the amount of chargers that our GM customers will have access to,” Barra said of Tesla. The savings come “because we’ve been able to do it faster and more effectively, and we’re really looking for ways that we can be more capital efficient as we go forward. So if there’s other opportunities to partner, we’re going to be very open to them.”

GM follows Ford Motor Co., which last month said it would give owners of its EVs access to about 12,000 Tesla Superchargers starting next spring through adapters. Ford also will stop building EVs with traditional Combined Charging System ports starting in 2025, instead using the NACS port used by Tesla.

Tesla operates about 17,000 charging connectors, and its fast-charging network is considered both the largest and most reliable in the U.S. Ford’s deal with Tesla is the first such agreement with another automaker, and some analysts have said it could open the door to future such partnerships.

With Tesla expanding access to GM and Ford vehicles, “the three U.S.-based auto companies are all on one standard,” Barra said Thursday. “I think that’s going to drive a lot of adoption.”

Automakers are trying to improve the charging experience before they launch EVs in high volumes. Nationwide, one in five charging attempts failed last year, according to J.D. Power. Tesla’s Supercharger network tends to have much better charger uptime than peers. Fewer Tesla drivers face charger outages and, if a charger is down, the driver typically finds a working charger at the same location, the firm said in February.

Musk, who has complained about not receiving enough credit for advancing EV adoption from the Biden administration, said his company will fully support GM vehicles at Tesla Superchargers and not give preference to Tesla owners. Musk has said in the past that he’s willing to help rival brands accelerate EV adoption in order to fight climate change.

“You have our full support and we’re incredibly excited to partner with you on this and just really make it a fantastic electric vehicle experience, whether somebody is driving a car from GM or from Tesla,” Musk told Barra during the announcement on Twitter, which he also owns.

Tesla’s decision to open its charging network to rival automakers has a few benefits for Tesla, including access to federal money for new charging stations. But it also removes one of the EV maker’s biggest advantages over competitors, analysts say.

The Tesla Supercharger network is considered the gold standard by EV analysts for its size, reliability and rapid growth versus other public charging providers. Tesla has more fast-charge units than all competing charging networks combined.

“This will really help put people’s mind at ease and we can focus on one standard and it’s really going to be great for consumers,” Musk said. “They just won’t have to worry about which plug, which socket, which charging station and it will just work seamlessly. So, I think this is going to be just a really fundamentally great thing for the advancement of electric vehicles in North America.”

With the opening of the Supercharger network, most EV owners will have access to both the Tesla network and competitors such as Electrify America, EVgo and Chargepoint. Although Tesla and the rival networks use different charging plugs, adapters make it possible for most EVs to use either charger standard using an adapter.

It was not immediately clear what the collaboration with Tesla will mean for GM’s dealerships and its ongoing charging partnerships. Access to Tesla’s network first will require an adapter, before the NACS connector is built into GM’s EVs, the automaker said. GM also eventually will provide adapters so that EV owners will be able to charge at stations with CCS ports.

A GM spokesperson said “charging adapters will continue to provide interoperability, including for charging infrastructure at our dealerships.” GM declined to provide additional details Thursday about the cost of adapters and how EV owners will receive one.

GM is working with charging network provider EVgo and Pilot Co. to install 2,000 fast chargers at as many as 500 Pilot and Flying J travel centers. The automaker also is working with its dealerships in the U.S. and Canada to install 40,000 Level 2 chargers in local communities — at locations such as restaurants, shopping centers and parks — by the end of 2026.

“We don’t see this announcement changing the collaborations with EVgo or Pilot Flying J, but rather enhancing what we will be able to offer EV drivers going forward,” the spokesperson said.

The CCS port was becoming the national standard charging connector, and many charging companies with CCS ports are expected to apply for funding through the National Electric Vehicle Infrastructure Formula Program. The CCS port runs one connection between the charger and the EV, said Conrad Layson, senior alternative propulsion analyst at AutoForecast Solutions. Tesla’s NACS port exchanges more information and usually leads to a smoother charging experience, he said.

EV chargers constructed with funds from the $5 billion NEVI program and a $2.5 billion discretionary grant program must adhere to minimum standards finalized by the Biden administration in February.

Under those standards, each charging port must have a CCS connector. However, ports are allowed to have other non-proprietary connecters, such as Tesla’s NACS, if the port is also capable of charging a CCS-compliant vehicle.

Tesla in November said it was making its previously proprietary EV charging port and connector available for “broad and open public use,” including to network operators and other automakers, according to the Biden administration.

Musk stressed that GM vehicle owners would not be treated differently than Tesla owners at Supercharger stations.

“I do want to reiterate to GM owners out there that Tesla is not going to do anything to prefer Teslas, so it really will be an even playing field,” Musk said. “I think people should feel comfortable buying a Tesla or a GM car and we will provide support equally to both. The most important thing is that we advance the electric vehicle revolution.”

Laurence Iliff, Hannah Lutz and Audrey LaForest contributed to this report.