Helmut Marko reveals the RB21’s biggest weakness after the difficult Brazilian Grand Prix. Helmut Marko analyses Red Bull’s difficult weekend in Brazil.

F1 | Red Bull, Marko on the major RB21 flaw: “The car has a very narrow working window”

Max Verstappen was undoubtedly one of the standout figures of the Brazilian Grand Prix, the twenty-first round of the 2025 Formula 1 World Championship, held last weekend at the historic Interlagos circuit. However, the Brazilian weekend was far from straightforward for the four-time world champion and for the entire Anglo-Austrian team, which experienced a dramatic shift in performance between Saturday and Sunday.

The Dutchman’s remarkable recovery drive demonstrated that change clearly. Starting from the pit lane, Max Verstappen produced an extraordinary comeback all the way to the podium, eventually finishing the São Paulo Grand Prix behind the McLaren of race winner Lando Norris and the Mercedes driven by Andrea Kimi Antonelli.

Discussing Red Bull’s performance in Brazil, Helmut Marko emphasized that the difficulties encountered with the RB21 were caused by an extremely narrow operating window, a limitation that inevitably influenced the problematic qualifying session. Both cars were eliminated at the end of Q1, a scenario that reflected the wider issues within the car’s setup.

“In Brazil we tested two different types of floor, but during qualifying we moved outside the working window in which the car operates in harmony with the tyres,” Helmut Marko wrote on Speedweek.com. He pointed out that the team still does not fully understand how they fell out of that ideal window. “In general, we are talking about the biggest flaw of the RB21 racing car: the car has such a narrow working window that even the smallest changes have a major impact; we are talking about variations of ride height in the range of half a millimetre or shifts in track temperature of only a few degrees.”

The Austrian advisor then added: “We are not the only ones facing this issue. Mercedes have struggled with it for a long time this year, and Ferrari have faced similar challenges. Thankfully, we managed to solve the problem for the race, and for me that is crucial, as was the team’s resurgence after a very difficult period during the summer.”

Concluding his analysis, Helmut Marko stated: “If in the end we lose the championship, the blame will lie with that period after the Imola weekend, when very little worked during half a dozen races.”