Button and team mate Fernando Alonso often suffered a competitive disadvantage last year because they were unable to deploy recovered energy at a rate similar to their rivals, but changes to the turbine and compressor of their Honda power units over the winter have, according to Button, solved the issue.
“The progress is massive in that area,” the 2009 world champion said. “That’s something we knew we had to work on. Deployment is not something we could work on massively last year with the compressor, but over the winter we’ve been able to [look at it] and Honda have done a great job in terms of bringing that to testing.
“We’ve had no reliability issues with it at all and it’s a big difference. At some circuits last year, in the race we were losing six tenths every lap because we didn’t have deployment. Now the system’s working well and from here on it’s marginal gains compared to our competitors. So it’s a good step forward and a necessary step forward.
“In qualifying we lost probably one or two tenths because we couldn’t deploy through a whole quali lap and now we can easily.”
Despite the improvements brought about by the latest specification of power unit, Button, who completed a further 121 laps in the MP4-31 on Wednesday, said there is still plenty of work for McLaren to do ahead of the season opener in Melbourne.
"I don't feel we've done any proper work yet with the set-up,” he said, “it's been mostly aero work and understanding if we're in the right place or not - not specific driver set-up work.
“The next two days are very important - we need two clean days, lots of laps, and lots of time on new tyres to really get a good feel for the car because we’re not there yet.”
WATCH: Button on McLaren's testing gains
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