Contrary to most observers' contention that the Red Bull Racing RB5 looks to be one of the quickest cars in the 2009 Formula 1 field, Mark Webber has expressed his fears that the Milton Keynes-based concern needs to extract more performance from its new mount if it is to truly be a contender this season.

Based on its initial testing form, the Renault-powered machine looked to be a quantum leap forward on all of RBR's previous efforts, with F1's master designer Adrian Newey seeming to have got a better handle than most on the sport's radical new regulations.

However, despite that early promise, both Webber and team-mate Sebastian Vettel were somewhat less optimistic about their prospects during the group test at Jerez in southern Spain last week, arguing that with time running out before the curtain-raising Australian Grand Prix in Melbourne at the end of the month, there remains much work to be done.

"We need to get a bit more performance," Webber told the Canberra Times. "I haven't really gone back to where we were when I first drove the car here [earlier in the year] and where I was very happy with it.

"We have to make the most of every run and understand as fast as we can. It's a bit hectic."

The New South Wales native was more positive, however, about his recovery from the broken leg he sustained following a mountain-biking accident during his annual Pure Tasmania charity outdoor adventure challenge last November - a setback that had left some wondering whether the 32-year-old would even be on the starting grid Down Under at all.

Webber admitted that at the moment he is finding driving the car significantly less of a challenge than merely making his way around the paddock on-foot.

"The hardest thing is walking at the moment," he confessed. "I am going easy on a bike and it's easy in the car.

"I have absolutely no problems in the car, and actually I prefer it that way than the other way around, walking beautifully and having problems in the car."