Vettel finds his voice: 'The race is under way. My best race? Still to come'
If he seemed to be falling out of love with racing, Vettel had been finding a new passion in activism, inspired by Lewis Hamilton's example in promoting diversity and equality. He was the first to join Hamilton in taking a knee before Grand Prix races, but his own primary interest lay in environmental action including helping workers clear up litter at Silverstone and encouraging schoolchildren to make bee hotels in Spielberg.
More recently it has extended to wearing a Pride flag in Hungary (for which he was reprimanded), speaking out about Russia's invasion of Ukraine, and criticising fans who harassed drivers in Austria.
Earlier this year he made an articulate and erudite appearance on BBC's Question Time political debate show. He admitted openly and honestly that his green stance was at odds with his profession, agreeing that the environmental impact of racing motor cars and jetting around the world meant he was inevitably 'hypocritical'.
Recently he's brought that sense of campaigning into the drivers' briefings, in a way that few of his contemporaries seem willing or able to do. He's been the outspoken, opinionated voice that modern day corporate F1 has needed, its moral compass, no longer afraid to speak out for what he believes is right.
If his activism succeeded in rejuvenating him on the track as well as off it, it's also meant that he's been taking stock about what's important in life. Away from the paddock, Vettel has always been very much a private family man. After nearly two decades of constantly travelling to Grand Prix locations around the world, the glamour and glitz of international motorsport has long since faded for the 35-year-old.
Maybe those two races he was forced to sit out at the start of the season proved to him that actually he doesn't miss being in the Grand Prix paddock anywhere near as much as he thought he would.
It might have put the thought into his head that perhaps it's time to move on to something new. Whether that's in racing (setting up a team in Extreme E, for example) or a related field (there's been speculation that he would love to complete an engineering degree), politics (he says not, which is a shame) or closer to home (perhaps in farming and agriculture), the next chapter of Vettel's life is still to be written.
As for how he will be remembered in the sport, his number of titles, records and achievements should speak for themselves. If he had retired at the end of that spectacular 2013 season then he would probably be heralded today as a candidate for the title of Greatest Of All Time.
But instead he stayed on and had the misfortune of running into the behemoth that was Mercedes, his successes in the sport brushed aside by Lewis Hamilton's litany of new records that have surpassed even those of Michael Schumacher.
Even his time at Red Bull is now being overshadowed by the recent successes of Max Verstappen. Maybe in the future, with proper distance and perspective, we'll be able to take a fresh look at Sebastian Vettel and his four world championships, 57 pole positions, 53 wins and 122 podiums over the course of 16 seasons, not to mention his pioneering activism.
In that spirit we'll leave the final word to the man himself: "I feel we live in very decisive times and how we all shape these next years will determines our lives," he said.
"Talk is not enough and we cannot afford to wait. There is no alternative. The race is under way. My best race? Still to come. I believe in moving forwards and moving on. Time is a one-way street, and I want to go with the times."