Formula 1’s customer-engine system is not doomed by rule. It is being exposed by reality. In 2026, teams can receive the same power-unit specification as their supplier’s works outfit and still find themselves fundamentally behind.

The reason is no longer simply horsepower. The new generation of Formula 1 cars has turned the power unit into a deeply integrated part of the entire performance package: cooling, packaging, electrical deployment, harvesting strategy, aerodynamics and drivability now overlap more than ever.

A customer team may receive equal hardware. It cannot automatically receive the same development timeline, the same engineering intimacy or the same freedom to shape the car around the power unit from day one.

The difference is not necessarily the engine itself. It is how completely a team can exploit it. The defining issue of Formula 1’s 2026 customer model

The myth of equal supply

The FIA framework requires power-unit manufacturers to supply customer teams with equivalent hardware. That principle matters. It protects the grid from an obvious and damaging form of competitive inequality: a supplier holding back a superior engine solely for its factory team.

But equality of supply is not equality of outcome. An engine is not a standalone item that can simply be dropped into any chassis without consequence. It is a system with thermal demands, electrical behaviour, software logic, packaging requirements and operational sensitivities.

Works teams develop those relationships internally. Their chassis engineers and power-unit specialists can work within the same programme, reacting together to a reliability concern or a newly discovered performance opportunity. A customer team works with a supplier, not inside one.

2026 has made integration decisive

Formula 1’s revised regulations have created a more electrically demanding era. The new cars require teams to make sharper decisions about where energy is harvested, where it is deployed and how the driver accesses the available performance around a lap.

Those decisions are not isolated from the rest of the car. A cooling layout affects bodywork. Bodywork affects aerodynamic efficiency. Aerodynamic drag alters the ideal deployment strategy. The car’s balance changes how aggressively a driver can use the available energy in different phases of a corner.

This is why a works team’s advantage is not necessarily visible in a dyno figure. It is visible in how quickly it reaches a complete solution. The factory car is designed around the engine; the customer car is designed with an engine whose broader development picture is owned elsewhere.

McLaren has made the problem impossible to ignore

McLaren’s 2026 campaign has become the clearest illustration of the new imbalance. The team uses Mercedes power but has openly acknowledged the difficulty of fully exploiting it against the Brackley works operation.

The point is not that McLaren has received an inferior unit. Andrea Stella has instead highlighted the reduced opportunities available to a customer team: fewer chances to integrate, to remain on the same timeline when issues emerge, and to connect power-unit learning directly to the chassis programme.

That nuance matters. Blaming a supplier for deliberate inequality would miss the actual problem. The disadvantage is structural. Mercedes can align every major decision around its own car first, because its power-unit and chassis operations are part of the same competitive machine.

• Packaging: Works teams can shape the car around the power-unit installation from the earliest design phase.
• Reliability response: Internal teams can react on one programme and one timeline.
• Energy deployment: Learning how to use the system efficiently is now a major performance differentiator.
• Development direction: Factory teams naturally optimise the next step for their own chassis first.

Why customer teams still matter

Calling the model a total failure would go too far. Customer teams remain essential to Formula 1. They reduce the financial barrier to entry, make the grid viable for independent constructors and give teams access to competitive technology without the immense cost and risk of building a power unit from scratch.

History also rejects the idea that customer teams cannot win. McLaren’s recent championships, Brawn GP’s 2009 title and Red Bull’s success as a Renault customer demonstrate that a great chassis operation can overcome the factory-team advantage.

The more accurate conclusion is harsher and more useful: customer status is no longer a neutral choice at the start of a major power-unit reset. It can work brilliantly once the rules mature and the learning curve flattens. At the beginning of a new technical era, it is a vulnerability.

A customer team can still win—but it must compensate for a disadvantage the works team does not have. Formula 1’s new competitive reality

What Formula 1 must decide

The sport now faces a policy question. Is it enough to guarantee identical parts, or should the rules also encourage a more equal flow of information, calibration support and integration opportunity between suppliers and customers?

That is difficult territory. Formula 1 cannot force a manufacturer to surrender every competitive insight developed by its own engineers. Nor should it erase the reward for building a complete works programme. But the championship must recognise that parity on paper can be misleading when the decisive gains come from the knowledge surrounding the part.