Four-time world champion Sebastian Vettel smashed the lap record at Montmelo in Formula One testing on Thursday when he clocked 1min 17.182 in his Ferrari but dismissed it as insignificant.
The German driver, who completed 188 laps, improved on the previous best set just 24 hours earlier by Australia's Daniel Ricciardo in a Red Bull.
"The times on these test days don't mean much," said Vettel.
"The important thing is that the car has proved to be very strong, allowing us to run all day without any significant problems.
"We are still working on some things for the first race and it's not really possible to make any predictions based on the performance of the other teams, because everyone is running a different programme."
Reigning world champion Lewis Hamilton and Mercedes teammate Valterri Bottas were in eighth and ninth places respectively with 1:19.296 and 1:19.532.
Just like Vettel, Hamilton refused to see pre-season testing as a potential reflection of what lies ahead in the world championship which gets underway in Australia in just over two weeks time.
"The track is very different to what it used to be because they resurfaced it," explained Hamilton.
"So it's difficult to know what all the experience means once we get to Melbourne. But, I definitely feel that we're moving in a positive direction."
Red Bull's Max Verstappen recorded a modest best of 1:19.842 off 187 laps, the second slowest of the day as drivers opted to focus on set-up.
"Today was about doing a lot of laps... a lot of laps," said Verstappen.
"The focus for us today was on long runs and the feeling with the car was good. No problems with the car and I was happy with the pace. We can definitely work from here. If it's going to be good enough, we'll have to wait and see."
Friday will be the final day of pre-season testing before the 2018 world championship gets under way in Melbourne on March 25.
Sebastian Vettel (GER/Ferrari) 1:17.182 (188 laps), Kevin Magnussen (DEN/Haas-Ferrari) 1:18.360 (153), Pierre Gasly (FRA/Toro Rosso-Honda) 1:18.363 (169), Nico Hulkenberg (GER/Renault) 1:18.675 (79), Carlos Sainz (ESP/Renault) 1:18.725 (69), Stoffel Vandoorne (BEL/McLaren-Renault) 1:18.855 (151), Marcus Ericsson (SWE/Sauber-Ferrari) 1:19.244 (148), Lewis Hamilton (GBR/Mercedes) 1:19.296 (84), Valtteri Bottas (FIN/Mercedes) 1:19.532 (97), Robert Kubica (POL/Williams-Mercedes) 1:19.629 (73), Sergio Perez (MEX/Force India-Mercedes) 1:19.634 (159), Max Verstappen (NED/McLaren-Renault) 1:19.842 (187), Lance Stroll (CAN/Williams-Mercedes) 1:20.262 (67)
© 2018 AFP