Theissen regrets overloading Vettel

Vettel starred in his role as Friday driver for BMW-Sauber from the Turkish Grand Prix, and his performances were so impressive that the team decided to keep him on for the remainder of the season.

That decision meant Vettel was forced to undertake a punishing end to the year because as well as the long-haul Chinese, Japanese and Brazilian Grands Prix, he was forced to fly back to Europe several times for his Formula Three Euro Series campaign.

With Vettel's title charge falling apart in the final races of the year to hand the crown to ASM teammate Paul di Resta, BMW motorsport director Mario Theissen has confessed that it was probably wrong of the team to give Vettel so much F1 responsibility.

"I am a bit concerned about the situation," he told autosport.com. "In my view, it was a bit too much for him in the past eight to 10 weeks. Doing F1, doing F3, doing all these obligations and also meeting obligations beyond the track, especially which were new for him, meant he is a bit exhausted now. I think he needs a break."

Theissen, who has been a big supporter of Vettel for several years, goes as far as suggesting that the young German's failure to win the F3 title was directly related to his F1 responsibilities.

"Yes, I think so," he said. "He would never admit that, and certainly when he is in the car he doesn't feel that. But there is a certain amount of work that you can do and if you go beyond that then quality will suffer."

The experience of this season has also probably played a key factor in the decision to race Vettel in the Renault World Series next season, which features just nine events. It would have been very difficult for Vettel to have competed in both GP2 and F1 practice at Grands Prix meetings next season.

Although Vettel is already a firm favourite to be promoted to a race seat at BMW-Sauber in 2008, Theissen insists that such a decision is still far from being made.

"It is too early to say," he said. "Obviously if we put a driver in the car as a test driver, we always have the idea of having him as a race driver. But if it happens in 2008 I cannot say that."