Lewis Hamilton pronounced himself impressed with the speed of his "well-behaved" new McLaren after day two of the second pre-season test in Spain.
Hamilton managed 120 laps in the MP4-27 at Barcelona's Circuit de Catalunya.
"The car behaves well in the high-speed corners," said Hamilton. "The baseline of our car is higher than last year, and it's better overall at high speed."
The 27-year-old was sixth on the timesheets, with Force India's Nico Hulkenberg quickest on the day.
The German's best lap of one minute 22.608 seconds was 1.198 seconds faster than the Briton's.
Hamilton said: "To have completed more than 1,000 kilometres in the past two days is incredibly encouraging. The whole team should feel proud.
"It's been an extremely productive few days, and I think Jenson [Button] will continue to improve the car tomorrow.
"Now I'm just looking forward to the final test [in Barcelona from March 1-4]. It's where you get a really good feeling of where the car will be.
"It's also exciting because it's the last stop before the first race."