Lewis Hamilton has praised the way that Mercedes developed this year's car over the course of the season.
The W10 made a lacklustre start to the campaign in pre-season testing in February at Barcelona, where it was clearly second-best to Ferrari's SF90.
But the Mercedes engineers got to work and were able to quickly turn things around, transforming it into a title-winning package as the year progressed.
"When we started this season, our car was actually a real heap to drive," Hamilton admitted at the FIA Prize Gala in Paris when he received his trophy for a sixth world championship.
"It wasn't that great looking at the testing," he continued. "We couldn't quite get it in the window.
"It wasn't until the last day that we got it to work, and then we went to the first race and we already had some great results."
The team's impressive 1-2 victory in Melbourne was a big surprise, and set the tone for the rest of the season where the Silver Arrows continually found a way to come out on top despite an ever-narrowing advantage over their rivals.
But while the season might have been one of the closest and hardest for Hamilton in recent times, he insisted it had also been one of the most enjoyable and that it had pushed him to new heights.
"It's been a good year," Hamilton said. "It's been the best year I would say in my whole career."
"Qualifying wasn't as strong this year," he subsequently told Motorsport.com. "Qualifying was still good, but it was a harder car to drive this year.
"But still, I was qualifying front row - top three quite often - and split the Ferraris when they all of a sudden had 30bhp more than everyone.
"The races were just as strong as last year," he added. "The races are really where the championship was won.
"[And] I've just been happier in collaboration with the team in terms of teamwork."
Hamilton admitted that events off the track - including the passing of one of his heroes and mentors Niki Lauda, and the fatal accident that claimed the life of F2 driver Anthoine Hubert at Spa - had also had a significant impact on his in 2019.
"There's quite a few people that we've lost so it's been quite an emotional rollercoaster," he said.
"From race one, to Monaco, to Spa, which were big, big dents in the motorsport world. And I think for everyone, they were struggling."
On the upside, Hamilton's been actively promoting a plant-based diet that he credits for giving him more energy and greater mental stability.
And his ventures into the world of fashion have also gone down well with his legion of passionate supporters around the world.
"My fans have been amazing, supporting me with it," he commented. "The doors that have been opened in terms of fashion, that's been well received and well accepted."