An updated engine for Fernando Alonso, and a raft of new aerodynamic concepts, helped the team deliver one of its most competitive outings of the season in Austin.

And although a solid double points finish was wrecked when Alonso suffered a loss of power, racing director Eric Boullier thinks that the potential is there for an encouraging end to the campaign.

"Obviously it is very positive for the team, especially for the end of the season to keep the morale for the winter," he told Motorsport.com. "It is also a bit of a reward for everybody who has been working hard.

"We went from so far behind and everybody has been working, working, working, passionately working. So it is good to see a little bit of encouragement."

He added: "The team did a good job to use any opportunity to get back where we would have been and we had some signs this weekend of rewarding the progress of what we are doing.

"We are not competitive yet, but clearly you can see there are some efforts, so it is good."

Double improvement

With the upgraded engine and new aerodynamic package having arrived at the same time, Boullier thinks it hard to work out just how much each element has contributed to the step.

But he thinks the fact Button was strong in the end was encouraging for understanding how much progress has been made on the chassis side.

"It is difficult," he said. "At least, I think, everything is working and everything is delivering on the track, which is important.

"Jenson was competitive [in Austin] and he just benefited from the chassis upgrade, so that was quite encouraging."