Honda and Nissan sign software and ECU sharing deal for fiscal 2029

What the two companies agreed

Honda and Nissan signed a joint development agreement on 31 August 2026 to standardize electronic control units, the in-vehicle operating system, and key middleware and vehicle control software for next-generation software-defined vehicles, with deployment planned from fiscal 2029. The pact covers high-performance main ECUs, the central computers built on systems-on-chip, and zone ECUs that manage functions in front, rear and cabin areas of a car.

The companies said the aim was to "strengthen competitiveness through improved R&D speed and investment efficiency." The agreement requires no equity swap or holding company, and it does not make either brand a subsidiary of the other. Mitsubishi Motors, in which Nissan holds a 26% stake, said it is actively considering joining the collaboration and remained in discussions with both carmakers on possible areas of partnership.

The shared operating system is designed to support over-the-air software updates, a capability Japanese automakers have been criticized for lagging on.

Why cooperation replaced a merger

Honda and Nissan signed a memorandum of understanding in December 2024 to combine under a joint holding company, with a Tokyo listing targeted for August 2026. The combined group would have ranked third by volume behind Toyota and Volkswagen, and the deal was valued at about $60 billion. Talks collapsed after just seven weeks over terms including the integration ratio, which sets how much each company is worth relative to the other.

Honda proposed changing the structure so that Nissan became a subsidiary through a share exchange rather than an equal partner, and Nissan refused. Nissan chief executive Makoto Uchida told his Honda counterpart Toshihiro Mibe he wanted to end discussions, and the two sides terminated the memorandum on 13 February 2025. Uchida stepped down the following month and Ivan Espinosa took over. Reuters reported, citing six people familiar with the matter, that Nissan insisted on near-equal treatment despite its weaker position and resisted Honda's pressure for deeper factory cuts.

In an interview with Yahoo Finance, Espinosa said there was "no discussion around integration" and that talks with Honda were project-based. He said the discussions were "very constructive" and that news would likely come in three areas: US manufacturing capacity, hardware for electric vehicle architectures including a possible common software stack, and battery supply for hybrids in the US.

What happens next

The two companies had already agreed in March 2024 to study cooperation on electrification and vehicle intelligence, and widened that into joint research on software-defined vehicles five months later. Honda's May 2026 business briefing confirmed management was exploring software-defined vehicle and software cooperation with Nissan, and Nikkei reported in late July 2026 that operating system standardization discussions were underway.

The pressure that pushed them together remains. Chinese rivals have taken share in Europe and Southeast Asia with cars heavy on software features, and US tariffs on Japanese-built vehicles have cut into margins. Both companies need scale to absorb the cost of EV platforms, autonomous driving and connected-car software, where smaller Japanese players face a structural disadvantage competing independently.

Nissan has been cutting roughly 20,000 jobs and closing seven factories worldwide as part of its turnaround. It returned to an annual operating profit under Espinosa's restructuring plan and posted 16 straight months of US sales gains, while Honda slipped to its first-ever annual loss. The software agreement gives both companies a way to share development spending without combining their balance sheets.