Michael Schumacher indicated he was pleased with his Mercedes team's work following the end of testing at Valencia on Thursday.
Schumacher enjoyed a trouble-free session on his first full day of running, the German covering 110 laps on his way to the ninth quickest time of the day. He admitted he was very positive about the handling of the new Mercedes.
"We were able to achieve a lot of valuable mileage and it was a positive day," said Schumacher. "I am pleased with that, and with how the car was behaving. Again, of course, this is not our final race car for the season but a lot of elements have already proved to be a significant step forward.
"I felt totally comfortable in the car immediately and noticed how much I had missed driving since November. We have a lot of work ahead of us, and this week gives us a very good idea of where we should concentrate our work. I look forward to going to Jerez now."
Team boss Ross Brawn was also happy, seeing that the car reacts well to the setup changes.
"We're starting to get an insight into the car's behavior and its responses to various setup changes are proving to be very consistent. After a few difficulties at the start of the test, we have finished with a strong day providing plenty of data and options to take forward to the next test in Jerez."