Mercedes made up for lost time on Sunday as the team completed a full day of testing with their 2012 challenger, the W03, in Barcelona.
The Brackley squad, who used a 2011-spec car during the first pre-season test, was allowed to do some private running after opting to sit out the final day of testing in Jerez last week.
There were no mileage restrictions for the test at the Circuit de Catalunya, and both Michael Schumacher and Nico Rosberg spent some time behind the wheel of the W03.
"[The] W03 had a second track outing today as we completed a private test in Barcelona," the team said via Twitter.
"Michael drove this morning and Nico this afternoon. Over 300km completed for our testing programme with the new car. To confirm: under the testing agreement, not running on the final day of the team test in Jerez allowed us to nominate a private test day."
The team will officially launch the W03 just before the second test gets underway in Barcelona on Tuesday morning.
