F1 2027 and 2028 Engine Rule Changes: Why the FIA’s Power Unit Fix Changes the ADUO Fight

F1 has agreed the engine fix that spent months looking impossible. The FIA, FOM, teams and all power unit manufacturers have signed off on a two-stage rebalancing of the ICE and ERS split across 2027 and 2028, shifting the ratio from today’s effective 53/47 to 58/42 in 2027 and 60/40 in 2028. Internal combustion engine output rises in two steps, fuel flow increases follow the same staged path, and harvesting power goes up while overtake mode stays where it is. The package goes to the World Motor Sport Council for formal approval on June 23 in Macau. It lands in the same week the ADUO verdict named Red Bull as F1’s benchmark ICE and handed Mercedes, Ferrari, Audi and Honda varying levels of upgrade headroom. That changes the target every manufacturer is now building toward.

Key Points: Key Points: F1 2027 Engine Rule Changes and the 2028 Shift

• ICE/ERS split moves from 53/47 today to 58/42 in 2027 and 60/40 in 2028, reducing electrical power’s share across two seasons
• ICE max power rises from 400kW to 420kW for 2027 and 450kW for 2028. Fuel flow increases 5% in 2027 and 13% in 2028
• Max harvesting power increases from 350kW to 375kW in 2027 and 400kW in 2028. Overtake mode stays at 350kW
• Agreement requires at least four of five manufacturers to sign off. All five are on board
• World Motor Sport Council approval vote set for June 23 in Macau
• Changes land the same week ADUO confirmed Red Bull as the benchmark ICE, with Mercedes getting one upgrade and Ferrari, Audi and Honda getting two

What Has Been Agreed

The headline number is the ICE/ERS split. The 2026 regulations launched on a notional 50/50 basis between combustion engine and electrical power, though the real-world figure settled at approximately 53/47 in favour of the ICE. That ratio moves to 58/42 in 2027 and 60/40 in 2028, giving the internal combustion engine a progressively larger share of total power output across the next two seasons.

The mechanism for getting there is a two-step increase in ICE output. Maximum power rises from 400kW to 420kW in 2027, then to 450kW in 2028. Fuel flow follows the same logic: up 5% for the first year, up 13% for the second. Those are not small numbers across a season of racing, and the 2028 figure in particular represents a substantial shift from where the 2026 rules began.

On the electrical side, harvesting power increases at both steps. The current 350kW maximum for harvesting goes to 375kW in 2027 and 400kW in 2028. Overtake mode stays at 350kW throughout. The FIA’s framing is that these changes address energy management problems and make qualifying more flat-out without touching the racing characteristics that have produced exciting grands prix this season.

Why It Took This Long

Getting four of five manufacturers to agree was always the threshold. Every manufacturer had a different reason to resist faster or deeper change.

Mercedes wanted the full 50kW shift for 2027. That would have meant proper hardware revisions across all manufacturers and Audi was not having it. Having just invested in its first full works F1 power unit project, being asked to redesign hardware within one season of the new rules was a non-starter. Ferrari’s objection ran through a different logic entirely. Any rule change giving manufacturers freedom to redesign would hand Mercedes a development window it did not need, on top of the ADUO upgrade it had already earned.

The 2027 step is modest enough that it may not force hardware redesigns. That’s the compromise that got Audi over the line. The 2028 step is large enough that proper development work will be needed, but manufacturers get a full season’s runway to prepare for it. It’s not what Mercedes asked for. It’s workable for everyone, which is why it got across the line.

2026 F1 Power Unit Suppliers

ADUO upgrades don’t just apply to the manufacturer. Every customer team running that power unit gets the same spec when it lands. That makes the upgrade picture significantly larger than five manufacturers suggests.

The ADUO Overlap

The ADUO verdict confirmed in Monaco identified Red Bull as the benchmark ICE on the FIA’s performance index. Mercedes trails by more than 2% and gets one upgrade this season and one for 2027. Ferrari, Audi and Honda are all more than 4% behind and each get two upgrades in 2026 and two more in 2027. Those upgrades flow to every customer team on that power unit. Ferrari’s two upgrades reach Haas and Cadillac. Mercedes’ single upgrade reaches McLaren, Williams and Alpine. Honda’s upgrades reach Aston Martin, while Audi benefits as a full works entry. That’s nine of the eleven teams on the grid moving forward with upgraded power.

What looked like a catch-up mechanism for the chasing pack reads differently alongside a rule change that increases ICE output. Every manufacturer is developing toward a moving target. Those with two ADUO upgrades available have more headroom to shape their engine around the new fuel flow limits. Mercedes, with one upgrade, is working with less flexibility. Red Bull gets no ADUO upgrade at all and cannot touch its ICE outside normal homologation rules, even as rivals build toward a 420kW and then 450kW ceiling. That’s the uncomfortable part of being first in this system. But there is a flip side. Red Bull now knows exactly what the 2027 and 2028 targets are. They can’t change the current engine. What they can do is design every decision between now and the regulation change around hitting those ceilings as efficiently as possible, as long as it all complies with what’s on the books today. That forward planning is available to every manufacturer on the grid, tokens or not. The team that maps its current development most intelligently toward the 2027 spec doesn’t just close the gap. It arrives at the new rules already pointing in the right direction. The cost cap is the constraint on how aggressively any of them can run that overlap. Within it, the planning advantage belongs to whoever reads the new targets most clearly.

Ferrari spent the months before Monaco resisting the 60/40 shift specifically because it did not want to give Mercedes a free development window while ADUO remained live. Now Mercedes has an ADUO upgrade anyway and the staged rule changes are happening regardless. Ferrari’s original objection is now harder to hold in the same shape. Whether it pushes harder for the faster timeline or focuses its two ADUO tokens on closing the gap within current regulations is the strategic question heading into the Spanish Grand Prix weekend.

What It Means for Qualifying

The FIA specifically named qualifying in its framing of these changes. The energy management complaints from drivers this season have centred on the deployment rules that make a marginal throttle input mid-corner trigger downstream power penalties costing half a second on a qualifying lap. Oliver Bearman described losing two tenths in China despite his best corners, tracing it back to a 5% battery deficit caused by a near-invisible throttle action. Charles Leclerc flagged a two to three percent throttle lift at one corner costing him half a second on the following straight.

Increasing ICE output while keeping overtake mode at 350kW shifts the balance of a lap toward the combustion engine’s contribution. A flat-out qualifying lap relies less on ERS deployment optimisation and more on driving the car. In simple terms, the driver gets more lap time from pushing the car and less from nursing invisible battery maths. The qualifying lap drivers have been asking for since Melbourne gets closer. Whether the 2027 step is large enough to fully resolve what drivers have been describing won’t be known until the cars run under the new rules. The intent is clear. The execution is a 2027 answer.

Coffee Corner Take

Every manufacturer in this room had a reason to block this. Audi didn’t want to redesign an engine it had just built. Ferrari didn’t want to hand Mercedes more room to develop. Mercedes wanted bigger change faster than anyone else would accept. Five manufacturers, five different agendas. The fact it got agreed tells you less about consensus and more about who had the most to lose from walking away empty handed. This is F1 politics dressed as a technical announcement.

The staged approach is what made it possible. A 20kW increase in 2027 may not force hardware redesigns. Audi can live with that. A 50kW jump in one go was a different argument entirely. Mercedes didn’t get what it wanted either. It wanted the full shift now. What it got is a slower path that still ends in the same place.

And then there’s the part of this story that I can’t prove but I can’t ignore either.

My read is that Mercedes may have managed the early-season compliance picture very carefully. Not sandbagging. Not turning the engine down. More a case of operating within the rules in a way that left its ICE sitting inside the ADUO eligibility window when the first review period arrived. It’s not confirmed. There is no document that says that was the calculation. But the manufacturer powering the team that has won every race so far in 2026 has just received an ADUO upgrade for itself and its customer teams. If you were planning a season around a regulatory system you understood better than most, that is a very clean way to run it.

There’s one more thread here. Mercedes were required to introduce a mandatory compression ratio change from Monaco onwards. Monaco is a street circuit where outright power has almost no space to express itself. The change came in and nobody could tell whether it had moved anything. Barcelona this weekend is the first real circuit test of whether that adjustment has actually cost Mercedes performance, or whether they absorbed it without blinking. If they’re still fastest in Spain despite the change, the theory gets harder to dismiss.

The other side of this that does not get enough attention is Red Bull actively arguing with the FIA that it is not the best ICE. A manufacturer named as the benchmark by the governing body’s own assessment is publicly disputing that verdict. That says plenty about the system ADUO has created. Being first closes doors. Being behind opens development headroom. If you want the full background on how ADUO works and what was predicted back in April, I covered it in detail here.

June 23 in Macau is expected to be the rubber stamp. The politics have already moved. The more interesting question is what Ferrari does next. Chase the 60/40 timeline harder, or focus the two ADUO tokens on closing the gap before the rules shift again. The engine war just got more complicated. Mercedes power may have the cleanest route through it, but nobody is building toward the same target they were a week ago.