Koji Sato, Toyota’s vice chairman and the man who stepped back from the CEO role earlier this year, is asking Japanese automakers to stop competing on the things that do not matter and start sharing them instead.
Sato also chairs the Japanese Automobile Manufacturers Association — JAMA — which covers every major Japanese brand from Toyota and Honda down to smaller operations like Daihatsu. This week he made the case publicly: Japanese automakers should standardise basic parts across manufacturers. Wiring harnesses. Cooling components. Fasteners. The unglamorous infrastructure that every car needs and that currently gets designed and sourced separately by each company.
The reason is China. And the timeline is now.
What Sato Is Proposing
The proposal is not about sharing engines. Nobody is asking Honda to give up VTEC or Subaru to abandon its flat-four. The signature technologies that differentiate Japanese automakers from each other and from the rest of the world are not on the table.
What Sato is pointing at is the layer below that — the standardised components that connect and support the parts buyers care about. A wiring harness does not define a car. It connects it. A fastener does not express a brand’s identity. It holds the car together. When each Japanese automaker designs, sources, and stocks these components independently, they are all paying separately for the same problem.
Standardisation across Japanese automakers would mean shared supply chains for these parts, lower per-unit costs, and freed-up engineering resources that currently go toward reinventing the same solutions across multiple companies.
This Already Happens — Informally
Cross-brand parts sharing is not a new idea in Japan. It already exists at the informal level.
Mitsubishi and Subaru were genuine rivals through the 1990s and early 2000s rally wars — the Galant VR-4, the Lancer Evolution, the Impreza WRX STI, the Legacy RS. The rivalry was genuine. Pop the bonnet on a current WRX and Mitsubishi parts are in there — diamond logo and all. The rallying war did not stop the supply relationship.
The rivalry at the top did not prevent pragmatic parts sharing at the component level. What Sato is proposing is extending that logic formally and systematically rather than letting it happen by accident of supplier relationships.
The Historical Precedent
Japan has done this before. The 1950s version of the Japanese auto industry was a collection of small, fragmented manufacturers producing cars that the rest of the world largely dismissed. The quality gap was real.
Government pressure pushed the industry together between 1960 and 1970. Smaller companies folded into larger ones. Production went up. Quality went with it. The Fairlady SPL213 of 1960 — a modest and obscure roadster — and the Datsun 240Z of 1969 represent the span of how quickly Japanese automakers moved when they moved together.
The specific consolidations matter. Toyota absorbed Hino. The result, eventually, was the Hilux pickup — one of the most successful commercial vehicles in history. Nissan absorbed Prince Motor Company. The result was access to Prince’s engineering talent and, ultimately, the Skyline GT-R nameplate. Consolidation in Japan has a track record of producing both corporate survival and enthusiast-grade results.
Sato is not proposing mergers this time. The scale of the intervention is different. But the logic is the same: Japanese automakers pooling resources produces better outcomes than Japanese automakers competing on costs they cannot afford to duplicate.
The Chinese Context
The comparison to China is the reason this conversation is happening now rather than in five years.
China’s automotive industry in the 1990s was roughly where Japan’s was in the 1950s — state-directed, quality-inconsistent, and not taken seriously in export markets. The difference is how fast the trajectory changed. China’s government directed the investment, set the targets, and pushed manufacturers toward specific technologies. Market economies do not work that way.
Electric vehicles became the accelerant. Chinese manufacturers were ahead on EV volume before most Western or Japanese manufacturers had committed to the technology seriously. BYD, CATL, and the ecosystem around them developed at a pace that was not predicted accurately by most industry analysts outside China.
Japanese automakers have strong internal combustion expertise, strong quality reputations, and strong dealer networks in established markets. They are at risk in markets where those advantages matter less than EV technology and price. Standardising parts does not fix the EV gap. It does free money and engineers that could go toward fixing it.
The Enthusiast Case For It
First instinct when hearing about shared parts across Japanese automakers: concern. Shared parts across Japanese automakers sounds like a step toward homogeneity — the same components under different badges, diminishing what makes each brand distinctive.
That concern applies to the wrong layer of the car.
Mazda’s identity lives in the MX-5’s handling, the rotary’s sound, the steering weight. Not the harness. Subaru’s identity is the flat-four, the AWD, the way a WRX feels on a wet road. Not the fasteners. None of what matters about these brands is in the parts Sato is proposing to standardise.
The argument actually runs the other way for smaller Japanese automakers. Mazda and Subaru are small companies operating in a market where scale determines cost. When Mazda’s engineers spend time on wiring harness specifications that could be standardised with Honda and Toyota, those are hours not spent on the next Miata. When Subaru’s procurement team is sourcing unique fasteners, that is cost that does not need to exist.
Greater standardisation on the basics could give Hiroshima’s engineers more room to make the MX-5’s replacement a genuine home run. It might give Subaru the resources to bring back the WRX STI. The brands that would benefit most from this kind of cost relief are the ones enthusiasts care most about.
The Bigger Picture for Japanese Automakers
Sato’s call this week is about wiring harnesses on paper. What it is really asking is whether Japanese automakers can pull together under competitive pressure the same way they did in the 1960s.
That time around: government pressure, companies setting aside rivalry, shared acknowledgment that standing still was worse than changing. Those same conditions are back. Nissan is under serious financial strain. Honda and Nissan have been in merger talks. Smaller brands face being priced out of markets where Chinese competition hits hardest.
Parts standardisation is not the answer. It is the start. The 1960s consolidation did not produce the Datsun 240Z immediately — it built the ground the Datsun 240Z could grow from. Sato is proposing ground. What Japanese automakers grow from it is what comes next.
FAQs
What did Koji Sato propose for Japanese automakers?
Greater standardisation of basic parts — wiring harnesses, cooling components, fasteners — across all Japanese automakers to reduce costs and simplify supply chains.
Who is Koji Sato?
Toyota’s vice chairman, former CEO. Chairs JAMA — the body that represents all major Japanese automakers.
Why are Japanese automakers considering cooperation now?
Pressure from Chinese competition. Chinese automakers have moved rapidly in EV technology and price competitiveness, threatening Japanese automakers in multiple markets.
Does parts sharing mean all Japanese cars will become the same?
No. The proposal targets infrastructure components — harnesses, fasteners, cooling parts — not engines, platforms, or brand-defining technologies like Honda’s VTEC or Subaru’s flat-four AWD system.
Has Japan done this before?
Yes — 1960s consolidation under government pressure. Toyota took Hino, Nissan took Prince. Production and quality both improved quickly.
Which Japanese automakers would benefit most?
Smaller brands like Mazda and Subaru stand to benefit significantly — they carry the same fixed costs as larger manufacturers but with far less volume to spread them across. Freed-up engineering and procurement resources could go toward product development.
Does this already happen?
Yes, informally. Mitsubishi parts are in the Subaru WRX right now — rivals on the rally stage, supplier and customer everywhere else. Sato wants that formalised.
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