Jenson Button says McLaren's MP4-30 has improved ten-fold since winter testing after completing the first day of practice at the Circuit de Catalunya.
Button and McLaren returned to the scene of the second and third winter tests, which were riddled with reliability issues for the team as it adjusted slowly to life with Honda power. In those tests McLaren was running with the power turned down - so much so Button says he could take the final two corners flat out - in order to gather as much data as possible without being limited by reliability issues.
The MP4-30 ran with a new livery in Spain and Button thinks making a comparison between the car underneath the paint between February and May is unfair.
"I don't think you can compare it, it's very different," Button said. "The last corner is not easy flat now, whereas then it was easy flat through the last chicane and last corner. No, it's a massive difference from winter testing. We've also been able to put mileage in now which is a big change. The circuit is probably slower because of the heat and the wind but the car feels ten times better than it did then."
Button's option tyre run in FP2 saw him break into the top ten, something McLaren has not been able to replicate in qualifying or a race so far this season. His final position of seventh, 1.9s down on Lewis Hamilton, is encouraging given the fact McLaren has brought new parts and an upgraded power unit to Spain but Button thinks it would be foolish to get carried away.
"It's still only practice. We always seem quicker in P2 than in qualifying. We'll see, hopefully we can have a clean weekend and then we'll see where we stand. I'd say it's a promising day when you compare us to the front guys anyway. It's the closest we've been all year.
"It's always nice seeing that on the timing sheets but it is only practice. It's been a weird day. On the prime tyre in P2 I really struggled and on the option tyre was much better. Really weird ... Trying to work out why that is. P1 was much better on the prime tyre and I was very happy with it. A lot of set-up changes, a lot of different things on the car today with both of us, so hopefully we get a lot of information and sort out what's best for tomorrow."