Explaining The FIA Engine Rule Update That Shuts Down A Potentially Massive Loophole

The 2026 season will see huge changes to what Formula One cars look like, how they operate, and ultimately, how races might turn out.

Although Lando Norris will enter as reigning champion thanks to his victory in the 2025 Drivers' Championship, reports have emerged that Mercedes look the strongest out of any team entering next season, and therefore the pack could be shuffled.

Teams that manipulate ambiguous rules can give themselves a massive advantage over the rest of the pack, especially in years where there are huge shifts in regulations, but the FIA has recently issued an update that shuts down a potential cheat that could have been used to give a significant boost.

Fuel flow meter reading could have been tampered with under previous ruling

Refuelling has been banned in F1 since 2010, but fuel still plays an extremely important role in the sport to this day. — Refuelling has been banned in F1 since 2010, but fuel conservation still plays an extremely important role in the sport to this day. | Gary A. Vasquez-Imagn Images

A shift in the way F1 limits fuel usage meant that, for 2026, the rule capped the energy the fuel can deliver, rather than the fuel flow's weight per hour.

To ensure this rule actually serves its purpose, the FIA approved a fuel-flow meter, made by Alengra, to monitor how much fuel energy is entering an F1 car's engine.

One problem. Changing the temperature of fuel can alter the density of it, potentially allowing the sensor in Alengra's flow meter to output an incorrect reading that gives a wrong measurement if the meter was either warmed or cooled.

The FIA noticed this issue, and subsequently added a rule that bans 'any intentional heating or chilling of the fuel-flow meter." Case closed, or so it seemed.

Mercedes committed the most notorious example of loophole manipulation, with DAS (Dual Axis Steering) in 2020. — Mercedes committed the most notorious example of loophole manipulation, with their DAS (Dual Axis Steering) causing significant controversy in 2020. | David Kirouac-Imagn Images

However, a team could effectively put down any difference in their car's fuel-meter temperature to an adverse effect of an entirely separate system within the engine, therefore causing the temperature difference to be indirect.

After a recent FIA council meeting, the final adaptation of the rule was introduced, reading:

“Any device, system, or procedure, the purpose of which is to change the temperature of the fuel-flow meter is forbidden."

This loophole getting shut down does not inherently mean that F1's governing body was suspicious about any particular team using such a method, and in fact, could have been a concern raised by a team itself.

This change is one of two issues that are currently on the radar of the FIA, with a potentially much bigger story coming from Mercedes' and Red Bull's rumored tampering with their cars' compression ratios, which could lead to both teams getting more energy into their cars compared to the rest of the grid.

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