Lewis Hamilton and Valtteri Bottas, who are both using different chassis this weekend in France, also had new engines fitted into their W12s ahead of round six at the Azerbaijan Grand Prix.
Mercedes are widely known for building the most durable engine in the turbo hybrid era, which is why Horner was caught off-guard when he heard the news.
“I was surprised that Mercedes changed engines so early,” Horner told Sky Sports.
“We haven’t seen that in recent years, usually they have lasted the longest. Maybe they have a bit more degradation than they expected. I don’t know, we are driving according to our plan.
“The hardest thing to predict is how many races we will have in the season. There are some bumps at the end of the year.”
Horner’s reaction came after Honda introduced their new power unit in France, one round later than Mercedes, which could potentially have an impact if that pattern continues further into the season.
We had a good Friday and improved quite well during the day. On this open track with gusty winds, it’s not easy to nail the lap, but we had a good end to the day. Enjoyed my flying lap 😎 #KeepPushing #FrenchGP 🇫🇷 pic.twitter.com/Fg2lLQ8CWZ
— Max Verstappen (@Max33Verstappen) June 18, 2021
Meanwhile, the saga surrounding Pirelli and their tyre issues in Azerbaijan rumbled on, with the tyre manufacturer looking to absolve themselves of blame for the incident, claiming the running conditions of the tyres at the time contributed to Lance Stroll and Max Verstappen’s high-speed crashes in Baku.
Verstappen disagreed with the results of Pirelli’s investigation, but the teams have been instructed to increase the pressures of their tyres this weekend as a result.
Horner weighed in on the debate, but said Red Bull followed Pirelli’s advice at every point throughout the Azerbaijan Grand Prix weekend.
“Firstly, we were just pleased that no driver was injured the week before last because obviously accidents on that straight with walls in close proximity are never good to see,” Horner said.
“We worked fully with Pirelli and the FIA to for them to try and understand what’s gone on because we have worked within the guidelines and prescriptions that Pirelli and so on come up with.
“So then you’ve got to ask yourself, why did it happen? So the result is that obviously pressures have been increased. Is 2psi enough to prevent [that] something might happen again? I don’t know.
“We obviously need to rely on Pirelli and their technical expertise. But hopefully we won’t see incidents like we’ve seen obviously in Azerbaijan.”
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