The high-downforce 2017 rules package created much faster grand prix cars after a period of reducing speeds that started with a bid to remove downforce in 2009.
"I find it a little surprising", Horner told Autosport. Obviously we had the change for everyone but I think they are a bit harder, so for me it was pretty straightforward as I said because I was happier with the auto with that tyre. It's shifting a little bit too much, we set the vehicle up for this, then the tyres move that way or the track moves that way. The Soft tires felt pretty good in Q2 so we chose to use them in my last run. "It's a bit like cruising to America and changing direction 100 times", said the German.
"I guess I can't really expand too much on it because if we knew it all we could do it, and also we're constantly working on solutions, set-up direction, or getting to the auto to optimum set-up on the weekend has been interesting", he said. Yet Mercedes signed him to another one-year contract in September to remain with the team through the 2018 season.
"It's incredible the technology we have and what we're doing with it". "We should be at least as fast as we are this year but just making racing better". The decision has already taken a lot of criticism from the paddock, but now two of the most influential drivers on the grid have spoke against them.
"I think you should ask us what we need to overtake".
"Not to say that we know everything, but we know how the cars feel", he said.
"For me it's really how can I utilise these tyres, how can I minimise the losses, and not go in the wrong direction on set-up, which we have done a couple of times".
Red Bull opted to run on the slower medium tyres as Daniel Ricciardo clocked fifth fastest, followed by the improving Haas duo of Kevin Magnussen and Romain Grosjean.
F1 is in its second year under the ownership of US -based Liberty Media, which has also been instilling changes to try to further promote the series.
The tweaks to the new regulations include a simplified front-wing, with a larger span, and low outwash potential, as well as a wider and deeper rear-wing. The changes include a simplified front wing and brake ducts and a bigger rear wing flap to make DRS more powerful - all of which will make the auto less aerodynamically efficient and slower compared to its 2018 counterpart.
"For me it's not about setting records everywhere", he added.