BMW: No regrets about letting Vettel go

Vettel was a BMW Sauber test driver and, after making his F1 debut for the team at the 2007 United States Grand Prix, a deal was agreed with joint-backers Red Bull for him to move to Toro Rosso for the second half of last year.

Although BMW Sauber made the decision to let Vettel go because they had no space at their team at the time, Theissen says he has had no second thoughts about having let him slip through his fingers for now.

"No," he told autosport.com when asked if there were any regrets about his Vettel decision.

"Red Bull and BMW have supported him over many years and it was clear that for the early years of his career it would be the right move to gain experience without too much pressure.

"He is just 21 - with just one year of experience. He has another 15 years ahead of him."

Theissen believes Vettel has made tremendous progress as a driver since he joined Toro Rosso.

"Definitely," said Theissen. "When he started with Toro Rosso as a racing driver it was clear he would need a learning period but that has been tremendously short.

"It was an immaculate race in Monza. Toro Rosso put the best car on the grid for these weather conditions and he did an immaculate job without being under pressure at any point of the race.

"It is fantastic. Just an amazing story - I am happy for Sebastian but also for Gerhard (Berger) and Franz Tost. We have worked together for many years and it is just incredible what they did at Toro Rosso."