Jenson Button says McLaren-Honda has slashed its lap times by 'four or five tenths' per lap after fixing its engine ERS deployment system over the winter and feels it is in a much stronger position after 12 months of experience with the new power units.

Last year McLaren's new partnership with Honda got off to a disastrous start with the team continually suffering power unit issues which curtailed its running time hugely during pre-season testing. As a marker of improvement, Button's 84 laps on the opening day of 2016 testing was more than the total combined laps McLaren achieved at last year's opening test.

On top of the reliability improvements Button says Honda has also got on top of its ERS power deployment woes during the winter and is confident it has found up to half a second per lap in gains.

"The positives are the deployment is so much better, I don't know if it is the same as the other guys out there but it feels like it is, that is a big step for us," Button said. "This isn't a circuit which you would struggle with deployment over one timed lap but over a long run we were struggling losing four or five tenths on a lap whereas now we don't lose that so in a way we have gained that time back on a long run.

"There were no negative bits to the car and today has been all about system checks and trying new things as there are lots of differences with this car and the engine. The standout today has been the deployment of power has been very good and consistent, quite a much better on longer runs than last year."

Despite the positive steps Button says he cannot assess the full performance of the MP4-31 as he spent the whole day running system checks and experimenting with different setting on the new car and hasn't yet begun working on race set-up.

"It is difficult to say in terms of power because this won't be the power unit we take to the first race," he added. "Much better, very easy to understand and play with it and it listens to change which is good. The rest of the car is being system checked so no real running or set-up work.

"Am I happy with the outright performance? I can't comment on that yet I think at the end of the test we will know a lot more."