Sebastian Vettel wasted no time at all in underlining Red Bull's raw pace at the Barcelona test on Wednesday, by setting the fastest lap at the circuit so far on his first morning back in the car.

The second day of the test saw all the teams bar HRT on track as they embark on their final push ahead of the first race of the season in Australia at the end of the month. The weather was again overcast with track temperatures falling short of 20C for most of the morning until the sun poked through the clouds just before lunch.

But Vettel was undeterred by the conditions and set a time of 1:21.865 to go over half a second quicker than team-mate Mark Webber's best time from day one. The world champion then helped his team work up an appetite ahead of lunch with some rigorous pit stop practice, lap after lap, in the final 30 minutes of the morning.

Ferrari made its return to the track with Felipe Massa at the wheel and a new exhaust system on the car, not dissimilar to Red Bull's. Massa set the third fastest time with a 1:23.324 at the start of a four lap run, but his work was focused on assessing the new parts on the 150th Italia rather than grabbing the headlines. The car looked consistent over medium length stints, as it has done throughout the testing season, suggesting that the new aero parts and exhaust have slotted in to place without issue.

Midway between Vettel and Massa on the timing screens was Vitaly Petrov, who started his last full day of testing before the first race of the season. He was working on some baseline set-up runs on new tyres, with a series of longer runs planned in the afternoon. He will share Thursday with Nick Heidfeld before handing the car over all together on Friday.

Further down the timesheets, Mercedes was testing a completely new rear end aimed at solving its overheating problems and clawing back the one second deficit it believes it has to the front runners. On the surface it appeared to improve reliability with Nico Rosberg completing over 50 laps, but with just the seventh fastest time it is not yet clear where the car will slot into the order. His father Keke was present in the paddock and was keeping in touch with his son's progress via a pair of team headphones.

Meanwhile, McLaren's luck appeared to go from bad to worse. An exhaust problem forced Lewis Hamilton to return to the garage at the beginning of what looked, judging by the number of laps on his pit board and his slow lap times, like a race simulation. After Jenson Button voiced his concerns about the car yesterday, the team is running out of time to get the MP4-26 sorted in time for the first race. The afternoon's progress will be telling before McLaren regroups off the track on Thursday ahead of a final assault on Friday and Saturday.

Another team with problems on Wednesday was Williams as Pastor Maldonado completed just five laps before a KERS issue stopped his car on track. The team is hoping the FW33 will return to the track in the afternoon, but the KERS has been removed.

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