Lewis Hamilton is cautiously optimistic over the performance of his new Mercedes car having finally managed to achieve some meaningful running on the final day of Formula One’s opening test in Barcelona.

The four-times world champion, who will begin the defence of his title in Australia on 25 March, completed 69 laps and set the fastest time of the week.

Because of the very cold and wet weather over the previous three days, including Wednesday being written off due to snow, Hamilton had completed only 25 laps and those with a low track temperature that prevented the car being pushed to its limit.

On Thursday afternoon, with the track reaching over 25C, the British driver was able to genuinely ascertain a feel for how his new ride, the WO9, is performing.

“I was really happy to get out, great to get on it,” he said. “To get a feel for the new car and so far it is positive. I’ve only had 60 laps but it definitely feels like a better car than last year.”

Hamilton won nine races on his way to the title in 2017 after what had, for a large part of the season, been a close fight with his Ferrari rival Sebastian Vettel. He was, he insisted, keen for another tight competition with the German.

“Definitely the closer it is the better it is when you win. You want the guys you are racing with on a level playing field so you can really show the differences between us as drivers.”

Hamilton also acknowledged the test marked the start of his bid to take a fifth title, which would match Juan Manuel Fangio’s achievement. “My mindset is really about learning as much as we can and being as consistent and diligent as you can with the laps you do get, but of course this is all foundations, building blocks for the title fight,” he said.

Vettel, whose Ferrari was quicker than the Mercedes on certain tracks last season, also made the most of the warmer weather by completing 120 laps; he was third fastest, nine-tenths behind Hamilton.

Vettel was also unwilling to read too much into what has been a limited testing period but hoped to be able to repeat his close battle with the British driver.

As was the case last year, he was eager to insist his rivals had the early advantage.

“I think Mercedes is the favourite,” the German said. “So if we can be close, very close, closer than last year, that would be great, and then we see from there. It’s a long time from here until the end of the season.”

Vettel led the title race until the 13th round at Monza in 2017 and at times enjoyed a distinct advantage over Hamilton. He acknowledged that he would be better able to judge his team’s chances when the second test begins on Tuesday next week in what is expected to be warmer weather at the Circuit de Catalunya.

“Overall it’s been a difficult week with cool temperatures,” he said. ”But I think it affected everybody. Limited answers. Still a lot of questions that we carry into next week.

“I think we understand what’s happening with the car. I think we can still understand more and understand better what’s going on with more running. But for that we need to run.”

McLaren, having switched to Renault engines this year, enjoyed a productive final day in what has been a generally positive test for the team. They lost time when a wheel came off on day one and to an exhaust issue damaging wiring on day two.

However, Stoffel Vandoorne completed 110 laps on Thursday and displayed positive indications that the car has some pace. He was second fastest, albeit on the fastest, hypersoft rubber.

Red Bull could not make the most of the time, with Max Verstappen completing only 35 laps after a reliability issue curtailed track time and a spin at turn 12 ended his running early.