Coulthard hails Red Bull's step forward

The Scot believes, however, that fighting for podium finishes this season is going to be very difficult seeing Ferrari's and McLaren's form.

"I think we've made a big improvement," Coulthard said. "But I think McLaren and Ferrari are at the front, and then there's a group of uncertainty with BMW, Williams, Renault and ourselves. A lot of guys fighting over four places.

"The podium will be difficult if all the McLarens and the Ferraris finish, but I think there's definitely potential to make this car quicker. We've got an area that we know is weak and we just need to be able to design and build the parts."

Coulthard's teammate Mark Webber, whose team finished in fifth place in last year's championship, also expects a very tight battle for fourth position this season.

"It's very tight between everybody," the Australian said. "We're on the back of the points at the moment I think.

"Between Williams, Renault and everybody it's very tight. Ferrari are on their own, then McLaren, then BMW, then the rest."