George Russell's Mercedes during first practice at the 2025 Singapore Grand Prix. Photo: Liauzh / Wikimedia Commons, CC BY-SA 4.0
George Russell left Baku with a trophy, a 66-point deficit to his own teammate, and a bill Mercedes has been deferring for weeks. Somewhere between now and Abu Dhabi, the No. 63 W17 is expected to take fresh power unit hardware, and fresh hardware beyond a driver’s season allocation is paid for in grid places. Whether it happens is barely a question anymore. The real story is what Mercedes gets in return, and the answer has been sitting in an FIA document since late August.
The catch-up engine the championship leaders qualified for
On August 26, the FIA published the results of the first two review periods for ADUO, the Additional Development and Upgrade Opportunities scheme built into the 2026 power unit rules. Mercedes was granted one extra homologation for 2026 and one for 2027. Under the scheme, that allowance only goes to a manufacturer whose Internal Combustion Engine Performance Index measured between 2 and 4 percent behind the best engine. Ferrari, Honda and Audi were each granted two per season, the tier for manufacturers 4 percent or more adrift. The second review window, which ran through Hungary, produced no new grants.
Count the names on that list and one manufacturer is missing: Red Bull Ford. By elimination, that makes the Red Bull Ford unit the benchmark the others were measured against, at least on combustion alone.
That is a strange place for Mercedes to be. Its drivers sit first and second in the championship, with Kimi Antonelli on 302 points and Russell on 236, and the team still qualified for a scheme meant for manufacturers that are behind. The contradiction has a simple explanation. In its own ADUO explainer, the FIA points out that the index looks only at the ICE and does not reflect full power unit performance, because the ERS carries so much of the output under these rules. Read the results together with the standings and the implication is clear. At least over the first part of the season, Mercedes’ edge did not come from the combustion side, so a sanctioned ICE upgrade adds performance where the package measured weakest.
Why the upgrade and the penalty arrive together
The FIA’s rules make two things matter. First, an upgrade granted for this season is lost if it is not introduced by the final race. Second, the permitted upgrade scope covers physical hardware: ICE elements, exhaust, turbocharger, MGU-K, electronics and more. New hardware means new elements, and once a driver has exceeded his season allocation, every additional element brings a grid penalty at the event where it is first used.
Russell has had technical problems at both Canada and Belgium, the kind of season that eats into a driver’s element pool. That turns the decision into a question of when, not whether. Ferrari went through the same exercise with Charles Leclerc in Baku. We broke down how Ferrari weighed its free upgrade against the grid drop, and the logic transfers almost exactly. ADUO comes with cost-cap relief for the development work. There is no equivalent relief on the starting grid.
Monza already set the benchmark, and the calendar gets tougher from here
Mercedes has done this once already. Antonelli took a full fresh power unit at Monza, started 19th, and won the race. Toto Wolff’s case for Monza was straightforward: long straights, plenty of overtaking, and “our calculations say that that’s the best track to take it.” The penalty cost Antonelli nothing.
That result is the reason Mercedes can treat Russell’s penalty as something to schedule rather than something to fear. It is also the trap in the thinking. Monza is the most forgiving venue in Formula 1 for a back-of-grid start, and the eight rounds that remain are not all as kind.
- Sepang (Oct. 2–4): F1’s return to the Sepang International Circuit runs as the Bahrain Grand Prix, relocated to Malaysia. Long straights open and close the 5.543 km lap, and Mercedes is bringing new W17 parts. Taking the engine the same weekend would combine two rounds of learning into one. The downsides: nobody on this grid has raced these cars there, F1 has not raced at Sepang since 2017, and rain is a live possibility.
- Singapore: Russell won there from pole last year. It’s a tight street circuit with a sprint on the schedule, which makes it the worst place to start from the back and the most rewarding place to start from the front.
- Austin, Mexico City, São Paulo: These are the classic penalty venues, with long straights and proven passing zones. They also come late enough that the upgrade would benefit fewer races.
- Las Vegas, Qatar, Abu Dhabi: Vegas has the straights for it. By Qatar and Abu Dhabi, the upgrade barely pays for itself. It becomes an engine fitted mostly to keep an allowance from expiring.
The trade-off is simple to state and hard to solve. Every race Mercedes waits cuts the number of weekends the new engine is in the car. Every race it brings the change forward puts a lower-mileage unit in a car whose driver cannot afford a DNF. And the choice of venue decides whether the penalty costs five points or fifteen.
The 66-point gap is bigger than it looks
Here is the point the standings table leaves out. Antonelli has already served his engine penalty, and he won the race anyway. Russell still has his to serve. So the effective gap after Baku is 66 points plus whatever Russell’s penalty weekend ends up costing him.
With 208 points still available (eight Grands Prix plus the Singapore sprint), Russell needs to outscore Antonelli by an average of 8.25 points per round to draw level. Baku showed what that takes. He won from pole and held off Max Verstappen by 0.196 seconds through two Safety Car restarts, while Antonelli crashed in qualifying, started 16th and recovered to fifth. That was close to the best possible weekend for Russell, and it closed the gap by 15 points. He did it without new parts, too. We noted on Thursday that Mercedes brought nothing new to Baku, and the car was fastest anyway.
For Mercedes, one variable matters most in all of this. Antonelli’s penalty came at Monza, with a car that could pass the whole field. Russell’s has to come somewhere else. If the W17 can repeat that kind of recovery at a second venue, the penalty costs little and whatever the new hardware adds is free performance for the run-in. If it can’t, Russell will have given up points he could not spare to make an already fast car a bit faster.
What to watch this weekend
The most useful document this weekend is the FIA’s power unit element list, published at every event. It lists each new ICE, turbocharger or energy store fitted to each car, and it will show whether Mercedes pairs Russell’s engine change with its Sepang upgrade parts before any press release does. For session times, the Mercedes parts list and the rest of the weekend’s storylines, see our Sepang race weekend notebook.
Mercedes’ last notable engine story at Sepang was Lewis Hamilton’s failure while leading in 2016. This time, whatever happens to a Mercedes engine in Malaysia will be down to a strategy call, not a failure.
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