BARCELONA // Thursday belonged to a new driver and today will belong to a new car, but yesterday it was the introduction of Mercedes-GP's latest upgrade package that set the paddock abuzz at the Circuit de Catalunya.
Michael Schumacher, the seven-time world champion, topped the time sheets in Montmelo with a fastest lap of 1min 21.268secs, eclipsing Sergio Perez, the Sauber rookie who posted the week's quickest time the previous day.
Schumacher's teammate and compatriot, Nico Rosberg, was third, behind local favourite Fernando Alonso, of Ferrari.
Schumacher had said on Thursday that while he was pleased with the progress the team was making, they were "not quite" in a position to win when the season starts at Melbourne on March 27.
However, following the fitting of a revised front wing, alternative brake ducts and new turning vanes, in addition to the new exhaust system and diffuser that had already been added, the Mercedes team appeared much improved on the Spanish asphalt during the penultimate day of testing.
"We have been developing the car step by step this week with new parts arriving each day," Schumacher said last night. "Our focus [yesterday was] on understanding how to get the best from the car now that it is pretty much in its final configuration for the first time."
Ross Brawn had said his team planned to complete a low-fuel, soft-tyre run before heading to Australia and Schumacher's speed yesterday indicated that was the case, a suggestion that Brawn later confirmed.
Any pace comparison with Red Bull-Renault would be thoroughly skewed at this stage as the constructors' champions have yet to run on a comparable fuel load and tyre compound.
Yet the Mercedes chief Brawn will be quietly encouraged by the lap times his tweaking has produced.
"We've definitely moved forward," Brawn told BBC Sport. "Whether it's enough we won't know until Melbourne. I don't believe one or two of the other teams have shown their full hand yet, but [our performance is] certainly a lot more respectable."
Red Bull did not show their hand yesterday, with Sebastian Vettel, the reigning world champion, completing only 64 laps - compared to Alonso's 141 - and spending extensive periods in the pit garage with engineers and team principal Christian Horner.
"I think we are reasonably prepared," Vettel said. "I think the last couple of years in the first races we didn't do very well. The championship starts straight away and every point in the end can be important [so] we need to have a competitive car from the first race onwards - and finish the races.
"There's always a lot of focus on making the car reliable, because even if you have a car that is one second quicker than everybody else, if you never finish the races you will never score any points, and you will not win the championship."
Vettel may have spent much of yesterday in the pits, but no car has spent longer in its garage than Hispania Racing Team's F111, which is yet to take to the track at all this winter.
It was finally unveiled yesterday and will today, on the final day of testing before the teams depart for Albert Park, complete its first laps of testing.
HRT, who announced only on Thursday that Vitantonio Liuzzi will drive for them this season, have seen their preparations hampered by a series of delays due to what Colin Kolles, the team principal, referred to only as "certain circumstances".
The F111 was expected to take to the track yesterday afternoon after its launch, but was delayed once more due to certain parts of the car's suspension being held up at Spanish customs.
"It's been a tough winter, but we've managed to have a new car in a very short time," Kolles said. "The F111 represents a significant step forward for Hispania Racing and we have made a big improvement for our second season in Formula One."
The Indian driver Narain Karthikeyan is unlikely to get behind the wheel today as HRT bid to provide Liuzzi with as much mileage as possible. Karthikeyan ran up plenty miles in the team's previous car, but is well aware that lack of testing does not set them in good stead for the year ahead.
"We are under no illusions that it will be a challenging season as we haven't used the car," he said. "I expect Australia to be a tough start."