BUDAPEST, Hungary -- Lewis Hamilton has said Sebastian Vettel is "one of the greatest people" Formula One has ever had, crediting the German for being one of few people who has joined him in being outspoken on social issues in recent years.
On Thursday four-time champion Vettel announced he will leave F1 at the end of this season.
As well as wanting to spend more time with family, one of the reasons Vettel cited for stepping away was to focus more on environmental activism, which has increasingly become one of the German driver's passions away from racing.
Hamilton and Vettel have comfortably been F1's most vocal drivers on a number of social and controversial issues, such as racial and gender inequality inside and outside of F1 as well as protesting anti-gay laws. They have both frequently worn Pride colours before races or on their race helmets in support of the LGBTQ+ community at races in certain countries.
Hamilton, F1's only Black driver, has recently set up a charitable foundation to help encourage more people from minority backgrounds into the sport and has called on F1 to do more to address the imbalance.
Hamilton said Vettel has been one of the few to stand alongside him in trying to promote change.
"When I talk about the journey that I've felt I've experienced in this sport and often feeling that it's been relatively lonely, he's one of the few people that's made it not feel lonely," Hamilton said on Thursday ahead of the weekend's Hungarian Grand Prix. "He stood by me through a lot of things.
"I always remember 2007, a press conference in Magny-Cours and him being very outspoken in a drivers' briefing and I knew then he would be a powerful figure in the sport. Then seeing his success and seeing that he puts others before himself... he's been so brave in speaking out and standing for what he believes in.
"I think he's one of the greatest people we've seen in this sport and we need more like him. Sad because I've lost an ally in this side of the sport on the grid, but I know that outside he will be doing great things and we will always remain friends and I hope there are other things we get to do together outside."
Hamilton dismissed the suggestion F1 will be worse off when people like himself and Vettel are no longer racing.
"No, we are hoping that our work leads it to a better place. The work Seb and I have been trying to do here, has been lighting a fire, sparking conversations to leave the sport in a better place than it was when we found it and Seb has had a huge role to play in that.
"There is still a lot of work to do, I don't know if Seb will continue the work in the background in the sport or not. But I do hope it will be in a better place and we have not wasted our time."
Hamilton and Vettel have both dominated modern Formula One, winning 11 championships between them since making their debuts in 2007.
Hamilton admitted their bond has improved as they've grown older, although he admitted they've never had time to meet away from an F1 setting, which is something he is hoping to change in future.
"I think when you're focused on winning championships and stuff... when we were younger, we didn't have time to stop and talk about what we do in our own personal lives or things we cared about. Over time we've started to see one another take those brave steps and standing up for things we believe in and been able to support each other.
"He's been so supportive to me and I'd like to think I've supported him also. I've come to realise we have a lot more in common than just the driving passion. It's really kind of been him standing out into the uncomfortable light and trying to do something with the platform that we have and I think that's why for me he's very much unlike any other drivers that have been here, past or present."
Hamilton also credited Vettel's on-track legacy, saying he's one of the best he's raced against.
"On the racing part of things, he was incredibly quick, very, very intelligent. Very good engineer I think, very, very precise on track. Just a great all-round competitor.
"Very fair but also very strong, firm on track. He's never been someone to blame other people for mistakes, he would always put his hand up and say it was his fault, which I always thought was honourable."
Thursday's media day for this weekend's Hungarian Grand Prix was dominated by talk of Vettel's retirement, which was announced just hours before press activities started.
Two-time world champion Fernando Alonso, who looks like a strong candidate to replace Vettel at Aston Martin next year, also spoke favourably about the German driver.
"We will miss him after so many years, sharing the track together, good fights," he said.
"Obviously in all his championships I was somehow in there as well! He's a great champion and also a great man, with very strong values, lovely family -- that is the decision also, into this, I heard [it's about] his family. So wishing him the best and hopefully he's around in the paddock in the future."