Months of discussions between manufacturers and the FIA are now moving towards a concrete agreement. Whilst the teams will strive to optimise every lap in this week’s Bahrain test, an equally important battle will be fought off-track.
The Mercedes engine, and its controversial compression ratio solution, has dominated F1 news in early 2026.
Rival manufacturers have all joined forces in pushing for the FIA to take action against a power unit that – from their perspective – violates the regulations.
Although Mercedes strongly dismiss these complaints, the pressure from the other engine suppliers is rising.
In an effort to reach a resolution and avoid a protest before the first race in Australia, the FIA have confirmed they are working to comprehensively settle this dispute before round one.
The FIA make declaration of intent
Nikolas Tombazis, the FIA’s single seater director, has been busier than usual this winter. With the 2026 season now approaching, teams want clarity on the Mercedes power unit.
As previously covered on LWOS, the Mercedes engine utilises a solution – likely involving thermal expansion – to increase its compression ratio above the 16:1 limit.
Because this trick only activates when the engine is turned on, the German power unit still passes stationary checks – which are conducted at room temperature.
Theoretically, this means the power unit is legal according to the current scrutineering procedures. However, other teams argue that exceeding the 16:1 ratio limit, on track or anywhere else, is unequivocally illegal.
There have been talks in recent weeks to address this issue before the Australian GP. One of the ideas being considered is to change the methodology used to measure compression ratio – instead conducting checks by turning on the engines in the garage.
Making this change would effectively prevent any engine from exploiting thermal expansion to increase compression ratio.
Of course, Mercedes are not in favour of this tweak being implemented. Toto Wolff argues that his team’s 2026 power unit is fully compliant with the regulations and current procedures.
Wolff also emphasises that Mercedes were assured by the FIA (upon first developing this technology) that it was permissible.
On the opposite side of the coin, rival manufacturers believe that introducing this new scrutineering procedure would simply ensure that the regulations are properly implemented.
Speaking in a recent interview, the FIA’s Nikolas Tombazis discussed the need to solve this dilemma:
“As these engineers are very clever and always pushing for an advantage,” Tombazis explained.
“Some have found ways to potentially increase it [the compression ratio] when the engine is running hot.
“And that is the discussion we’re having now… (cont. on next page)
09.02.2026. Formula 1, Cadillac Formula 1 Team Filming Day, Sakhir, Bahrain.