Nico Rosberg set the fastest time on the final day of Formula One testing Sunday, sealing impressive back-to-back performances by Mercedes after teammate Lewis Hamilton had been quickest 24 hours earlier.
Rosberg's time of 1min 20.130sec was also the best of any driver in the four-day session and also eclipsed the fastest times set in February's first week of testing at the same Catalunya circuit.
Hamilton had clocked 1min 20.558sec in the other Mercedes on Saturday.
Former double world champion Fernando Alonso, in a Ferrari, was the only other driver to break the 1min 21sec mark on Sunday, timing 1:20.494 while 2009 champion Jenson Button was third best in the McLaren in 1:21.444.
"I'm pleased with our pre-season testing programme. We have achieved a lot of mileage and I can feel that the balance of the car is good," said Rosberg, who put in 131 laps on Sunday.
"I have the general feeling that we are in a better position than in the second half of last year but this is testing not racing, of course."
The new Formula One season starts in Melbourne on March 17 and Rosberg was keen to play down the performance of Mercedes in winter testing, pointing to the dramatically different conditions that await the teams in Australia.
"The conditions in the first race will be completely different to here as it will be much hotter in Melbourne and Sepang (the venue of the Malaysian Grand Prix) so we need to wait and see."
Triple world champion Sebastian Vettel was down in eighth place in the Red Bull with a time of 1:22.514.
Mercedes team chief Ross Brawn believes the hard yards put in by Rosberg, who drove 2,640km in testing in Barcelona and Jerez, and Hamilton, who racked up 2,584km, will be crucial in the season ahead.
"I am pleased with the progress that the team has made over the last month and the steps forward that have been made with the car," said Brawn, who helped mastermind Michael Schumacher's title dominance in his Ferrari days.
"Lewis has settled into the team extremely well and everyone has enjoyed working with both him and Nico throughout the three tests.
"We're realistic about our performance here and our position once we get to Melbourne, and we look forward to the challenge of a new season ahead."
1. Nico Rosberg (GER/Mercedes) 1:20.130, 2. Fernando Alonso (ESP/Ferrari) 1:20.494, 3. Jenson Button (GBR/McLaren-Mercedes) 1:21.444, 4. Nico Hulkenberg (GER/Sauber-Ferrari) 1:21.541, 5. Kimi Raikkonen (FIN/Lotus-Renault) 1:21.658, 6. Paul di Resta (GBR/Force India-Mercedes) 1:21.664, 7. Pastor Maldonado (VEN/Williams-Renault) 1:22.415, 8. Sebastian Vettel (GER/Red Bull-Renault) 1:22.514, 9. Valtteri Bottas (FIN/Williams-Renault) 1:22.524, 10. Charles Pic (FRA/Caterham-Renault) 1:23.115, 11. Jules Bianchi (FRA/Marussia-Cosworth) 1:23.167, 12. Daniel Ricciardo (AUS/Toro Rosso-Ferrari) 1:23.628, 13. Max Chilton (GBR/Marussia-Cosworth) 1:24.103