Formula One champion Lewis Hamilton gave his new McLaren the seal of approval after getting back behind the wheel for the first time since he won the title last November.
However the 24-year-old Briton, who completed 81 laps in the MP4-24 in southern Portugal, warned his team had their work cut out ahead of the season-opener on March 29th.
Hamilton suffered an early setback before lunch when the car halted out on the damp track and had to be brought back on a truck.
The team said the car had experienced a "precautionary engine systems shutdown" which was rectified without having to change the engine.
Hamilton returned to the track in the afternoon and set the second fastest time of the 2009 specification cars.
Poland's Robert Kubica had an untroubled day testing the new BMW-Sauber in Valencia, eastern Spain, while Brazilian Felipe Massa completed 104 laps for champions Ferrari at the Mugello circuit in Italy.
