Lewis Hamilton has put the first laps on the Mercedes car he hopes will make him world champion for the fourth time in 2017.
The 32-year-old drove the new Mercedes W08 at Silverstone in blustery, damp conditions.
Hamilton said the car felt "incredible" and "pretty awesome" on his first outing.
It has been produced to new regulations aimed at making the cars faster, more dramatic and more demanding of drivers.
It features an elegant design, in contrast to some rivals, and a notably narrow rear.
Hamilton said: "Yesterday was the first time I saw [the car] together. It is the most detailed piece of machinery I have seen in F1.
"This is not an actual test - it's just a few laps to make sure the car will run. But I was able to go faster in the last couple of laps.
"It feels almost identical to last year's car in terms of ergonomics but you have this bigger, more powerful beast around you."
'You may see some sparks' - Bottas
His new team-mate Valtteri Bottas, signed by Mercedes last month to replace Nico Rosberg, who retired after winning his first world title last year, drove the car on Thursday afternoon.
Mercedes F1 boss Toto Wolff said he was hoping for a less fractious relationship between Hamilton and Bottas than between the Briton and Rosberg.
"It's a completely new dynamic," Wolff said. "I see it as an opportunity to start from square one with a healthy relationship. There are no games, no warfare because there is no history.
"There is a solid foundation that the relationship works well. But you have to be realistic that when they get out there, it is about winning races and championships, and the rivalry could be difficult."
However, Bottas told BBC TV that "you may see some sparks" and he wanted to be world champion himself at some stage.
"I am here to do a lot for the team, everything I can," he said,
"I'm here also to prove myself. I'm not here to be the second driver. We are both going to be fighting a lot on the track, but fairly, and for the team."
Mercedes have clearly worked extremely hard at shrink-wrapping the bodywork as much as possible around the engine and its ancillaries to ensure the cleanest airflow and maximum aerodynamic downforce.
And the aerodynamic detailing on the car looks especially intricate, with a cascading series of airflow conditioners - commonly known as 'barge boards' - either side of the cockpit, which are a clear advance on anything seen before in F1.
Bottas said: "What I really like about it is how clean it looks, but at the same time there's a massive amount of detail."
Wolff added: "It is a new era of technical innovation, maybe someone has found the silver bullet that makes the difference, like Brawn in 2009. Hopefully it will be us."
Fourth title 'there for the taking' - Hamilton
Hamilton is relishing the prospect of the new season, which starts in Australia on 26 March.
"It is a good day to get confidence in the car. It is a good way to brush off cobwebs and do the walking because next week we have to go straight into the running," he said.
"I definitely don't want to finish second. Every year you generally set the same goals but you might add more. All drivers want to win but not everyone has the ability or the opportunity.
"We will find out whether we have the car next week, whether it is a reliable fast car so I can exploit what's inside me. I am looking for that fourth world championship. It's there for the taking again, I am up against another great driver in Valtteri and hopefully Red Bull and Ferrari will be up there as well."
The new rules were introduced at least partly because Mercedes' rivals hoped a reset would allow them to make up some ground. But there was always a risk that the best team with the best engine would end up further ahead.
It's too early to say that, but the new car looks like a work of engineering art and Hamilton ought to be favourite to win a fourth world title this season.