Sebastian Vettel should have decided to retire from Formula One rather than continue racing, according to three-time champion Jackie Stewart.

After Ferrari and Vettel opted against extending their agreement beyond this season, the 33-year-old agreed to take a seat with the Aston Martin works team from 2021.

The four-time champion has struggled to mount a serious title challenge since joining the Scuderia in 2015, winning just 14 races in an era dominated by Mercedes.

Vettel admitted prior to signing with Aston Martin that retirement was an option he was considering, and Stewart thinks leaving F1 would have been a good choice.

Stewart told Stats Perform News: "Sebastian Vettel's a very nice gentleman. He's had a wonderful career and I personally would love to see him retiring and do what I do.

"Go to some of the best events, get involved with some of the best multinational corporations. He’d be a great ambassador for the sport apart from anything else. But if he wants to continue racing it’ll be because he loves the sport."

Vettel has scored just 17 points in the truncated 2020 season, with Charles Leclerc claiming Ferrari's only two podiums of the campaign.

The Scuderia are sixth in the constructors' standings and Stewart hopes their woes this year are not a sign of a long-term decline.

"Ferrari is one of the great brands that has ever lived. For whatever reason, this year has been a disaster for them. I hope and pray that next year we can see Ferrari as they really should be," he added.

Reigning champion Lewis Hamilton equalled Michael Schumacher's all-time record of 91 F1 wins at the Nurburgring last time out and could surpass him at the Portuguese Grand Prix next weekend.

Hamilton appears on course to match Schumacher's seven drivers' titles, but Stewart feels it is impossible to determine whether the Briton is the greatest driver of all time.

"It's a fantastic achievement to win as many races as he has. He's driving definitely the best car on the track," said Stewart.

"Nevertheless, he's driven extremely well but it's very difficult to say he was the greatest driver of all time. Was [Juan Manuel] Fangio better than Michael Schumacher? You don't know that. Was Arnold Palmer better than Gary Player? Or much more importantly was he better than all of the current golfers?

"But Lewis has driven extremely well and deserves the success that he has."