Button delighted with final preparations

Though the world champion ended the third day of the Barcelona test third fastest, 0.7s away from Nico Rosberg's ultimate pace, he was delighted by his McLaren's long-run pace in a full race simulation despite tricky weather conditions.

"Our race run was great," he said. "We didn't get any red flags until the last couple of laps of the last stint, so the boys did a great job with reliability, but also with pit stops.

"We went from having high fuel in the car to going out and doing some low fuel runs, and it is very difficult because you haven't done any set-up work. The day was too short for me really. I would rather have another day of testing.

"I know what I would do to the car to improve it, and hopefully Lewis [Hamilton] will be testing a few things that will be useful tomorrow.

"Because out of the box, with a new package, to be as consistent as we are and the pace we have, I am happy. I don't think we are at our maximum yet, but we will do our best tomorrow to get the maximum out of the car."

Button also expressed his conviction that there is much more to come from the 2010 package.

"This is all still very new, the actual car that we are driving now," he said. "We will see tomorrow, with a few set-up changes. I think the set-up changes that the team are thinking about could help us quite a bit tomorrow - and help the balance of the car.

"Our long run pace - I am happy with. There is still room for improvement. We are not getting the best out of the package we have and that is what we have to do tomorrow.

"I think it is just more time with this car - with this update on the car. More mileage, because it is a good update. It is a good amount. But it is just getting the best out of it, and we are not yet. We haven't done enough laps and enough set-up work."

Button added that he believed it was still difficult to predict the form ahead of the season opener, but said he expected some surprises given how close the field looks in testing.

"I think that if you look at the times today, the long runs, the Ferrari is competitive but we all knew that," he said. "Others, I don't really know about. It is difficult. I think the Sauber is going to surprise a few people, I think it is quicker than most people think and I think they will be up there at the first race.

"So, there could be five or six teams who are competitive and it is still all a bit of a guessing game at the moment and it will be until we qualify on Saturday in Bahrain.

"That is exciting I think. It is great for the sport, and I think it is exciting for the fans of F1 and all of us involved, because we don't really know what is going to happen."