Verstappen flags 'random' engine braking faults as Red Bull's new power unit passes Mexico altitude test

Max Verstappen emerged from the Mexico City Grand Prix at the Autodromo Hermanos Rodriguez with mixed feelings about Red Bull’s new in-house DM01 power unit, praising its altitude performance while flagging persistent and unpredictable engine braking behaviour that has troubled him since Austin.

The circuit sits at 2,286 metres above sea level — the highest on the Formula 1 calendar — and posed a significant unknown for all manufacturers operating under the sport’s new 2026 regulations, which remove the MGU-H that previously helped spool the turbocharger. Lower air density means the turbo must work harder to deliver the same oxygen volume as at sea level, directly affecting outright power from the internal combustion engine. Honda chief engineer Shintaro Orihara had warned earlier in the weekend that insufficient turbo boost at altitude would compromise what he called the “engine operation condition”.

For Red Bull Ford Powertrains, a newcomer to power unit construction, Mexico represented a literal baptism of fire. Team principal Laurent Mekies said the unit came through it better than expected. “Power unit wise, obviously it has worked well. So a huge well done and congrats to the guys,” Mekies said. “We knew that whatever we were going to see in Mexico would be considered as a one-off. We just didn’t know if we were going to enjoy a competitive advantage or a competitive disadvantage. But as it turned out, we were in the right mix.”

Mekies also noted the chassis coped well with the additional demands of Mexico’s altitude on cooling systems for both the car and brakes.

Despite that positive headline, Verstappen pointed to an ongoing issue with engine braking that has given him an inconsistent feel at the wheel across consecutive race weekends. The four-time world champion had already raised the problem in Austin, and he was back on the team radio with the same complaint in Mexico.

“It happens randomly,” Verstappen said in the post-race press conference. “The engine just decides by itself what to do, to be honest, so I don’t know. Maybe I need to have a conversation with the engine before going into the race. Maybe it has to behave better.”

The remarks underline that while Red Bull’s first self-built power unit has cleared its most demanding environmental test, refinement work remains ahead as the team looks to iron out the unpredictability that Verstappen has flagged across two consecutive rounds.