Fernando Alonso has said that he is not sure where he will line up on the Melbourne grid.
McLaren insist that they have improved since 2015, while Jenson Button described the latest engine step as the biggest Honda has made in 14 months.
However, Alonso, who just last week was linked with early retirement, warns that McLaren-Honda still have improving to do.
"We still have some power to recover, as the pre-season has been very short. Hopefully we can unlock the potential during the championship," AS quotes him as saying.
Alonso said one obvious step compared to 2015 has been better reliability.
"We can't forget that last year we used 12 engines for the world championship and it's impossible to think that can be repeated," he insisted.
"We have improved in some respects and there is still more to come so it's difficult to assess, but we are a little behind where we would like."
The Australian Grand Prix takes place on March 20.
