Sauber's Kamui Kobayashi became the fourth different driver to head the Barcelona testing timesheet as the second test of pre-season came to a close.
After Sebastian Vettel, Nico Hulkenberg and Pastor Maldonado had all ended one of the three previous days fastest, Kobayashi capped an unusually high-profile week for Sauber - on the timesheet at least - by moving to the front on the soft tyres in the final hour of the morning session.
The Japanese's eventual fastest lap of 1:22.312 was a mere 0.079s faster than Maldonado's hitherto overall benchmark from Thursday, with the Williams driver himself again running strongly to finish a close second in the FW34.
Both drivers comfortably cleared a century of laps for the day, clocking up 144 and 134 laps respectively, with the field as a whole generally showing hugely impressive reliability levels for this stage of pre-season - no fewer than six drivers completing more than 100 laps.
Force India's Paul di Resta was one of the drivers to get into three figures, this despite a morning excursion at Campsa which saw his VJM05 carted back to the pit lane. The Scot, nonetheless, returned to the track and joined in the now customary late morning fast laps, moving into fourth before taking third after lunch.
Jenson Button completed an impressive week for McLaren with the fourth-fastest time, the MP4-27 continuing to apparently run without reliability setbacks, as Ferrari finally notched up their first ton of the winter with Felipe Massa in fifth.
As the Maranello marque have stressed since the very first test with the F2012, they have continued to focus on data-gathering work but that is likely to finally change when the final test gets underway at Barcelona towards the end of next week.
After Vettel's flying start to the test, it proved a low-key end to the week for World Champions Red Bull as Mark Webber finished 1.4s off the pace in sixth place.
The Australian, who after his first day in the RB8 this week on Thursday reported a general lack of grip compared to last year around the circuit following the demise of the blown diffuser, spent longer than most in the garage after lunch before re-emerging onto the track for some longer runs.
Like Red Bull, Mercedes had a low-key finish to the week with Nico Rosberg appearing to focus exclusively on heavier fuel runs and therefore finishing eighth on the timesheet.
After problems galore with getting new signing Vitaly Petrov happy in the CT01 over the previous two days, Caterham had been hoping for a more straightforward final day with Heikki Kovalainen back in the car but ran into trouble after just 16 laps when an electrical problem necessitated a Renault engine change.
The Finn did return for the afternoon, however, and brought his lap count up to 70.
Marussia had gone into the final day with over 300 laps under their belt but they wouldn't add to that total on Friday as the discovery of a damaged suspension component to the right rear corner of the car ultimately side-lined the team for the whole day.
With the team finally planning to roll out their 2012 car for next week's Barcelona sessions, the problems meant it was a rather muted send off for the MVR-02 machine and, more importantly, cost French rookie Charles Pic a crucial additional day of track time as he gears up for his debut F1 season.
Day four times:
1) Kobayashi 1:22.312 144 laps
2) Maldonado 1:22.561 134
3) Di Resta 1:23.119 101
4) Button 1:23.200 115
5) Massa 1:23.563 103
6) Webber 1:23.774 85
7) Vergne 1:23.792 92
8) Rosberg 1:23.843 139
9) Kovalainen 1:26.968 70
