Tesla's electric charging network has long pleased electric car mavens. But Elon Musk's "superchargers" are now winning endorsements from a more unlikely group: other auto companies.

Ford was the first to announce a partnership with Musk in late May, followed by General Motors earlier this month. On Tuesday, EV truck company Rivian joined the bandwagon, saying it looks forward "to continuing to find new ways to accelerate EV adoption."

Under the partnerships, Musk has agreed to let consumers with autos from rival brands utilize its national network. 

Appearing with Musk on Twitter Spaces, GM Chief Executive Mary Barra said she was "really excited" to almost double the volume of chargers available to GM vehicle owners, adding that she hoped the Tesla system, known as the North American Charging Standard (NACS), could become a unified standard for the continent, which would "enable more mass adoption."