Franz Tost says Sebastian Vettel should stay at Red Bull long-term

The Toro Rosso team principal ran the German to his maiden grand prix win in Italy in 2008 before seeing Vettel leave for Red Bull the following year.

He believes that keeping a consistent line-up of drivers and team personnel is crucial to any outfit challenging for race wins and titles and thinks that Vettel, who is committed to Red Bull until at least the end of 2014, is in the best position possible.

"A team is always growing with its drivers, but it also can go down with its drivers. A driver is a very important factor in the team," he told the official Formula 1 website.

"When you look around, the really successful drivers stay with their teams for quite some time because the process of growing together - driver, engineers, car, tyres - all takes time and once you've grown into one single functional unit you want to keep that as long as possible.

"When it boils down to the sheer facts, for me the driver is the key to success."

Tost believes that Vettel has become the best driver in F1 and that he is central to any Red Bull success over the coming years.

"There will never be another Sebastian Vettel, just as there will never be another Michael Schumacher or Ayrton Senna," he added.

"Sebastian Vettel has become world champion because he has discovered himself - his own capacity and ability.

"The outside world can only provide the necessary environment, but it is always the driver who makes a team's success.