Horner hails his drivers' commitment

Although Coulthard is the oldest driver in the field, Horner is convinced that the Briton still has plenty to offer both Formula One and his team in 2008.

"David's motivation is unquestioned and he has worked hard over the winter, worked hard on his fitness and is probably more motivated than ever going into the new season," Horner said on stage at the Autosport International Show.

"As we have seen during recent testing, where Michael Schumacher, two years David's senior, again demonstrated his prowess behind the wheel - age is no barrier if you are motivated, committed, focused, and the motivation and drive is there."

Horner also paid tribute to the efforts of Coulthard's teammate Mark Webber, who came close to winning his first Grand Prix with Red Bull Racing last year.

"They are both seasoned pros, and I was extremely impressed with Mark in 2007," explained Horner. "He joined the team and his performances in qualifying were exemplary.

"Quite often he would take us by surprise with laps that appeared to come from nowhere, although he didn't have his share of luck on a Sunday.

"It was good to see a podium at the Nurburgring in atrocious conditions, and also what could have so easily been his first win in Fuji, were it not for the coming together that he had behind the pace car.

"(David and Mark) are two strong team players, they work well together, they are very similar in their approach, they are both extremely professional, dedicated F1 drivers and as team players they work very well for us."

Red Bull Racing are due to unveil their new RB4 at Jerez in Spain next week, with high hopes that the car can build on the speed of last year's car and overcome the reliability issues that cost the team a lot of points in 2007.

"The team grew considerably over the last 18 months," said Horner. "There has been sustained investment since Red Bull acquired the team in 2005.

"There is a whole sense that the team are more settled and more cohesive, as people have got used to working with each other. It is a reasonable sized team now, and we await the arrival of RB4."