Jenson Button says "there were no negative bits" to his car on the first day with the McLaren MP4-31 and thinks Honda has made a definite improvement with its ERS.
One of the main reasons behind Honda's struggles in 2015 was its deployment issues, which would see it lacking up to 160bhp on the straights after losing energy from the ERS. It often left McLaren helpless against other cars in a straight line but Button saw a genuine improvement on the first day of testing in Barcelona.
"It goes around which is a start and you need that first," Button said about the new car. "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 which is good. Obviously it shows other weaknesses in the car which we still need to improve but it has been a good day."
The 2009 world champion's positive mood echoes racing director Eric Boullier's, who said the MP4-31 is already better than last year's car. Button says improving the deployment accounts for a "four or five tenths" improvement alone and expects to see more from Honda before the Australian Grand Prix, where the Japanese manufacturer will bring a revised power unit.
"It is difficult to say in terms of power because this won't be the power unit we take to the first race. The positive 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. 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.
"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. It is good to see that all the hard work over the winter has really worked."
Button finished the day sixth, just under two seconds off the benchmark set by Ferrari's Sebastian Vettel, but says McLaren was not searching for quick lap times.
"Outright pace who knows, you look at the times you'd say we're miles away but we haven't been going out to set a lap time. Every lap I'm going different things with the steering wheel and my engineer is always talking to be so there are so many things that we are trying out, electrical things, which is very interesting so not a bad day."