Mercedes arrived at the Canadian Grand Prix with its first major upgrade package, featuring revised front wing, floor, and controversial spike-like profiles on the diffuser's upper section. These serrated extensions covered more than half the width, designed to effectively extend the diffuser and boost its aerodynamic effect.

Ferrari and other rivals raised concerns with the FIA, questioning the legality of the design and whether they could pursue similar solutions. The governing body responded with a technical directive following the Barcelona Grand Prix, clarifying that such extreme diffuser extensions would not be permitted going forward. This directive takes effect from the Austrian Grand Prix weekend.

Mercedes has acknowledged requiring minor tweaks to its diffuser to comply with the new guidelines. Media day in Austria revealed the changes, with spike-like profiles removed but extensions remaining to a lesser degree. Racing Bulls also received instructions to modify its diffuser extensions.

While the extreme Montreal-spec design is now prohibited, teams continue exploring diffuser extension concepts within revised boundaries. Ferrari's 2026 challenger and customer team Haas already show similar but less aggressive approaches, suggesting this aerodynamic battle will continue throughout the season.