Rosberg confident of 'significant' step

With the Brackley-based team having made good progress in the last two races, Rosberg says he is feeling confident that its aerodynamic development package will lift it even closer to the front of the field in Barcelona.

"I am very optimistic and very confident," said Rosberg, when asked by AUTOSPORT about his feelings for the Spanish GP weekend.

"Things are going in the right direction and we haven't really made that many big changes to the actual car, we've just been improving the car over the last couple of races.

"But now we have some upgrades here, so for sure there will be a step forward again. We went well in testing here, but testing was so long back that you cannot compare. I don't think it is going to be so different from Turkey to here, that all of a sudden with this track it will help us.

"The pace was what we had in Shanghai and Turkey and now we have upgrades and we are hoping to move a bit closer again."

Speaking about what kind of lift in performance the upgrades will deliver, Rosberg said: "Definitely a significant, clear step. It is bodywork, suspension and various other small bits, so it is definitely significant upgrades."

Rosberg also said that the criticisms that team-mate Michael Schumacher received after the Turkish Grand Prix had not affected the team.

"For me it is business as usual, and we are pushing on," he said. "We reviewed Istanbul, looking at what we could have done better because we didn't have a perfect weekend.

"Not only that, but we had a poor race pace compared to qualifying - and also an aerodynamic bit broke on my car for the last stint that cost me a lot.

"So there were various things that didn't go perfectly. We reviewed it and we are trying to get more out of it this weekend."