Venezuela driver Pastor Maldonado dominated the third day of Formula One testing on Thursday, giving Williams a timely boost ahead of the season opener next month.
Maldonado clocked the day's best time of 1min 22.391sec after completing 106 laps, having also been the quickest driver in the morning session.
Seven-time world champion Michael Schumacher was second fastest with 1min 23.384sec in his Mercedes while Japan's Kamui Kobayashi, in a Sauber was third best with 1min 23.582sec.
"I'm very happy with the race simulation that we ran this afternoon. It confirmed what we have seen from the first tests with our new car, and that we don't seem to have any big issues with reliability," said Schumacher.
"The small things from the last two days I would rate as typical testing issues. So from my side, I am happy with our first full testing session, and we have definitely improved our game which is what we wanted to achieve.
"To what extent, we can only see later, but I am finishing with a positive feeling."
Kobayashi also expressed satisfaction with his time, coming on his first day behind the wheel of the 2012 Sauber.
"It was my first day of driving the new car in Barcelona, and it was a good one," he said.
"We had no noteworthy problems all day and went through a lot of test items. I can feel we have made some progress compared to the test in Jerez. But, of course, we have a lot more work to do and there is room for improvement."
Meanwhile, Lotus were granted permission on Thursday to test at Silverstone next week after being forced out of the ongoing pre-season test here because of a problem with the car's chassis.
Testing concludes here on Friday with a final series at the same track again on March 1-4, before the teams travel to Australia for the opening race of the season in Melbourne on March 18.
Third day times:
1. Pastor Maldonado (VEN/Williams-Renault) 1:22.391 (106 laps), 2. Michael Schumacher (GER/Mercedes-AMG) 1:23.384 (127), 3. Kamui Kobayashi (JPN/Sauber-Ferrari) 1:23.582 (99), 4. Jenson Button (GBR/McLaren-Mercedes) 1:23.918 (114), 5. Jean-Eric Vergne (FRA/Toro Rosso-Ferrari) 1:24.433 (78), 6. Mark Webber (AUS/Red Bull-Renault) 1:24.771 (97), . Felipe Massa (BRA/Ferrari) 1:24.771 (84), 8. Paul Di Resta (GBR/Force India-Mercedes) 1:25.646 (83), 9. Timo Glock (GER/Marussia-Cosworth) 1:26.173 (108), 10. Vitaly Petrov (RUS/Caterham-Renault) 1:26.448 (70)