Carlos Sainz kept McLaren at the top of the standings on Wednesday, but the Spaniard does not have any illusions about the potential of Red Bull and Ferrari to break his record.
Sainz was found where his teammate Lando Norris had stopped Tuesday, recording the best lap in pre-season tests driving his MCL34 C4.
Despite the impressive performance, Sainz insists that McLaren is aiming for more progress in the last two days of preparation.
"The important thing to come out of these seven or eight days [is that] I think every time I'm on the track, the car progresses, "he said.
"I think that the balance of our car has improved in recent days, which allows us to extract a little more.
"But we still have a long season ahead of us where we have to keep working, we are still not where we want to be.
"That's definitely the right answer, and we have to keep working hard because a [1m]I think 17.1s around Barcelona is fast, but I'm expecting teams like Ferrari and Red Bull to go much lower and much faster than that. So, I am very careful and very calm. "
As for most teams, the McLaren MCL34 is a work in progress, and Sainz pointed to the changes the car had suffered since its debut on the track last week, with further modifications coming.
"Virtually everything has been improved," he said.
"We are working on underlying equilibrium issues and we will be able to get rid of them only if we make improvements to the car."
"So this is the purpose of Formula 1: decide what you need to improve, then try to make improvements in the following races to make it a bit better."
Although McLaren's performance has been positive, overall mileage in pre-season testing has been limited by small reliability issues. But discovering and solving initial problems is the very reason why a team performs tests, Sainz said.
"Every day you would like to do some more shopping, but that's what the tests are for," he said.
"Because if you do not find the reliability issues in the tests as we see now, it means that you are not covering enough work.
"We are having problems, but we are solving them and we are back on track like today and we have completed 130 laps with some problems, so that's good news and good progress."
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