Nico Rosberg denied Lewis Hamilton a clean sweep in practice ahead of the Spanish Grand Prix, although it was another Mercedes one-two.
The final hour-long session ahead of qualifying, however, was more about assessing different options than going for outright pace.
Rosberg topped the timesheet at Barcelona's Circuit de Catalunya with a lap of one minute 25.887secs, a third of a second slower than Hamilton's best lap from Friday's two 90-minute outings.
Hamilton himself finished 0.869secs down on Rosberg, and 1.2secs off the pace of his fastest of yesterday, underlining Mercedes' target of looking more at long-run, high-fuel simulations.
It was a similar story for their rivals, although the gap was again considerable, with Ferrari's Fernando Alonso third on the board, but 1.301secs behind Rosberg.
Williams' Felipe Massa was just a few hundredths of a second behind former Ferrari team-mate Alonso in fourth, followed by the Lotus of Romain Grosjean, but with the Frenchman 1.8secs back.
McLaren duo Kevin Magnussen and Jenson Button were sixth and eighth, sandwiching Red Bull's Daniel Ricciardo, a full two seconds adrift.
Sebastian Vettel, who missed most of Friday due to a wiring loom fault with his Red Bull, completed a session-high 20 laps as he attempted to make up for lost time.
The reigning four-times champion had to settle for the 10th fastest time, 2.2secs adrift of Rosberg, but with obviously far more remaining in the locker.
Down in 14th was Kimi Raikkonen in his Ferrari, 2.6secs adrift, with Max Chilton 19th, but only after ending his morning with another run into the gravel.
Chilton finished the second session by kicking up a pile of stones, and he did the same in FP3, although at least finished ahead of team-mate Jules Bianchi and Caterham duo Kamui Kobayashi and Marcus Ericsson.