Mercedes believes that Ferrari’s straight line speed in Austin is not as superior as it has been in previous events, but did not link the change to a recently-issued FIA directive.
A technical directive was issued to teams at the United States Grand Prix after an enquiry from Red Bull Racing, a tactic typically adopted in order to check on a legality.
It is understood that Red Bull proposed a system that would have permitted a team to run more than the allowed fuel flow amount, based on using electrical noise to disrupt sample pulses sent from the fuel flow metering units.
Red Bull is unlikely to have wanted to run such a device itself but wanted clarification based on a suspicion that a rival team was using such a ploy, and the FIA duly confirmed that such an approach would not be legal.
Ferrari was not named in any of the documents but rival teams have privately raised questions over the team's superior power advantage through this season.
Valtteri Bottas edged Sebastian Vettel by just 0.012s to claim Mercedes’ first pole position since July’s German Grand Prix.
“What’s come out this week has been quite interesting to see,” said Lewis Hamilton, who will start fifth.
“[In qualifying] I think they’ve lost a bit of power so it will be interesting to see how that continues and how that reflects in the race tomorrow.
“But they’re still quicker than us generally on the straights, so hopefully I won’t be struggling throughout the race.”
Mercedes team boss Toto Wolff said: “I think it’s very strong that the FIA issued a TD clarifying the situation with some very clear wording.
“But this is a process that is standard and has happened before and part of the role of the governing body.
“Certainly the three teams were much closer together in terms of straight-line performance here in the U.S., but I wouldn’t say this is down to any specific event.
“It is just a fact that we have won our first pole position since July in Hockenheim and we were really in the mix.”
