Red Bull believes a hydraulic failure caused Max Verstappen's car to stop on track during second practice for the Mexican Grand Prix and does not expect to take a engine-related grid penalty as a result.
Verstappen set the fastest time in both Friday practice sessions and finished the day with a 0.153s margin over teammate Daniel Ricciardo in second. The next fastest car was Carlos Sainz's Renault, 1.233s off the pace of Verstappen, while both Mercedes and Ferrari struggled for performance. As a result, Mexico could be Verstappen's best chance to win since his shock win in Austria earlier this year.
However, the Dutchman pulled to the side of the track with eight minutes remaining in the second session, prompting concerns that a Renault engine issue may be to blame and a grid penalty may be looming.
"At the moment we are not worried, we think it was a hydraulic failure," Verstappen said. "I don't know what it is exactly, as the car is still over there [on the other side of the track]."
Red Bull team boss Christian Horner confirmed the suspected hydraulic failure and, after Verstappen took a new power unit in Russia, he confirmed the Dutch driver had another engine available to him that could be introduced without penalty if he needs it.
"It's a hydraulic issue of some sort, so we need to get the car back to find out what's caused it and if it is an engine change then he has still got one in his pool and he should be alright," Horner said. "But first we need to get the car back to understand it."
Horner puts Red Bull's impressive pace down to the high altitude in Mexico City, which strips cars of downforce due to the thin air. It also means the turbo has to work harder to feed the engine with the same amount of oxygen as normal and Horner said the Renault engine seems to lose less performance than its rivals.
"I think what's happened here is this high altitude tends to even things out a bit and the engines, the brakes etc. are struggling for air, everything is struggling for air mass. We are running the same wing as Monaco here and we have the same downforce as Monza.
"I think we are able to run the car in its optimum state and we have a power unit that looks competitive relative to the others."