Honda admit they are surprised by how frequently Mercedes have changed their engines during the 2021 season.
The Silver Arrows have incurred grid penalties for fitting a new power unit at several races this year, particularly on Valtteri Bottas' car, with the Finn starting from the back of the field as a result.
Meanwhile, Lewis Hamilton has taken a new Internal Combustion Engine (ICE) for the Brazilian Grand Prix, triggering a five-place grid drop.
Mercedes have previously stated that they have used new engines to avoid any "catastrophic" reliability problems that could have a huge effect on the championship. Toyoharu Tanabe, Honda's F1 Technical Director, has been surprised by this.
"I'm very surprised," Tanabe told media, including RacingNews365.com, when asked about Mercedes' frequent engine changes.
"They are changing the ICE frequently. I cannot believe what's going on and why."
Christian Horner, Team Principal at Red Bull, acknowledged that Mercedes' decision to fit Hamilton with a new ICE in Brazil may have contributed to the Briton's significant pace advantage in Friday's qualifying session.
Hamilton qualified in first place for the Sprint Qualifying event, with Max Verstappen taking second.
"We saw from this morning that Lewis was very, very strong. That fresh engine is obviously pumping out some horsepower for him," Horner told Sky Sports.
"I think second was the best that we could hope for, so to be up there on the front row, we're OK with that."
Horner also believes that Verstappen would not have achieved the same kind of pace advantage if he too had had a new engine, due to the differences between the Mercedes and Honda power units.
"We don't see the drop-off that they do," Horner explained. "Maybe [a] maximum of a tenth between the start life and end life of a Honda engine, which is massively impressive.
"We don't have that degree of regular degradation."
The result from Friday's qualifying is still up in the air for Hamilton and Verstappen, with both potentially facing penalties for different infringements.
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