Red Bull chief Horner: 'Vettel can still improve'

(CNN) -- Red Bull's Sebastian Vettel dominated Formula One in 2011 en route to clinching a second consecutive world title, but team principal Christian Horner has warned his rivals the German can still get better.

The 24-year-old won 11 of 19 grands prix last season to become the sport's youngest double world champion, but Horner insists Vettel is still developing ahead of the 2012 season's opening race in Australia next weekend.

"Sebastian is still evolving," Horner told CNN. "He's still so young. He's still a relatively inexperienced grand prix driver.

"He achieved so much in his short time, to have won all the races he has, a double world champion, the youngest-ever double world champion."

Vettel also set a record for the most pole positions in a single season last term, starting 15 races from the front of the grid.

But, despite having won 20 races over the past three seasons, Horner insisted Vettel is still eager to achieve greater success in the future -- starting with the first race.

"He's hungry for more success. He's determined to try and defend his title in the manner in which he won it, which was obviously so convincing last year."

If 2011 was a vintage year for Vettel, it was a frustrating one for his Australian teammate Mark Webber.

Armed with the same RB7 car as his all-conquering colleague, Webber's only win of the year was at the season-ending Brazilian Grand Prix.

"2011 was a tough year for Mark," admitted Horner. "All credit to Mark, he kept plugging away. The biggest tonic for him was winning that final race in Brazil."

The 34-year-old is still searching for a first drivers' championship having finished third in each of the last two seasons. But Horner backed his driver and said: "He's going to be a fierce competitor this year."

After the opening race in Melbourne, the elite division of motorsport heads to Malaysia and China before the Bahrain Grand Prix -- scheduled to take place on April 22.

Civil unrest in the Gulf kingdom forced the cancellation of last year's event and there have been repeated calls for this year's race to be abandoned.

A spokesman for the Bahrain International Circuit told CNN earlier this month the grand prix will go ahead as planned and Horner said Red Bull trust the judgment of the FIA -- the sport's governing body.

"Bahrain has obviously been a topic of great debate," he said. "As a team we enter the world championship, if there's a race in Bahrain we'll be there. It's down to the FIA."