Kamui Kobayashi put Sauber at the top of the timesheets as Formula 1's second pre-season test closed.
The Japanese driver managed a 1m22.312s on Pirelli's soft compound in the final hour of the morning, the fastest time set over all four days in Barcelona.
Having ended the morning fastest, Kobayashi's time came under little threat in the afternoon as teams followed the established pattern of focusing on long runs.
The same was true of Pastor Maldonado, who got within a quarter of a second of Kobayashi in the morning before focusing purely on long runs in the afternoon - in the process racking up 131 laps over the course of the day.
Paul di Resta was the only driver to move up the order in the final session, as a switch to supersoft rubber produced a 1m23.119s - enough to demote Jenson Button and claim third.
Di Resta brought about one of the day's three red flags when he went off into the gravel on the outside of Campsa during the morning. The second and third came in the final 15 minutes, as a result of 'out of fuel' runs for Sauber and McLaren respectively.
McLaren driver Button was the last driver to get within a second of Kobayashi, although the Briton set his fastest time relatively early on in the morning on hard tyres.
Like Button and the three drivers ahead in the timesheets, Felipe Massa's lap chart also broke into triple figures. The Brazilian ended the day fifth fastest in the F2012, and completed several runs of around 13 laps each in the afternoon.
Mark Webber and Jean-Eric Vergne both added to their lap counts in the afternoon, but with neither improving their times, stayed sixth and seventh, separated by just 0.018s.
Nico Rosberg achieved 139 laps during the day, second only to Kobayashi, after completing a full race simulation in the morning and several shorter runs in the afternoon.
The German ended the day eighth fastest, ahead of Heikki Kovalainen in the Caterham CT 01.
The Finn's day was interrupted by an electrical problem that forced the team to make an engine change, but he was eventually able to complete 70 laps. His best time came late in the afternoon.
A suspension problem meant Marussia was unable to complete a lap on the final day of testing for its 2011 car; the new MR 01 set to be unveiled in time for the third and final pre-season test.
Friday's times: Pos Driver Team Time Laps 1. Kobayashi Sauber 1m22.312s 145 2. Maldonado Williams 1m22.561s +0.249 134 3. Di Resta Force India 1m23.119s +0.807 101 4. Button McLaren 1m23.200s +0.888 115 5. Massa Ferrari 1m23.563s +1.251 103 6. Webber Red Bull 1m23.774s +1.462 85 7. Vergne Toro Rosso 1m23.792s +1.480 92 8. Rosberg Mercedes 1m23.843s +1.531 139 9. Kovalainen Caterham 1m26.968s +4.656 70