Nico Rosberg gave Mercedes' 2011 car a fitting send off on day three at Jerez, but Lotus's Romain Grosjean was the fastest runner in a 2012 car.
Lotus fastest 2012 runner, Red Bull and McLaren close
Nico Rosberg gave Mercedes' 2011 car a fitting send off by topping the times on the third day of testing at Jerez - but, for the second day in three, it was the new-look Lotus team boasting the fastest 2012 machine.
With Mercedes not running on the fourth and final day of the opening test on Friday, Rosberg was therefore driving the W02 for the final time before the car is put into the F1 equivalent of 'retirement' ahead of the new W03's launch in time for the next test at Barcelona.
Just before 1pm local time the German became the first driver this week to dip below the 1min18sec mark with his lap of 1:17.613 more than enough to dislodge early pacesetter Romain Grosjean and remain unbeaten thereafter to make it two days at the top in a row for Mercedes.
Grosjean, though, will no doubt be pleased with his and the team's performance following his first ever test as an F1 race driver. At the close of play, the Frenchman was still in second place with a time eight tenths of a second clear of the next 2012 car.
In the closing minutes his E20 stopped on the track between turns three and four to bring out the day's third red flag, but that may have been explained by Lotus running a fuel-consumption check - and, anyway, by then he already had 117 laps on the board and made an impressive point.
The performances of Rosberg and Grosjean came on the day the bookmakers' three favourites for the 2012 Drivers' title - reigning two-time champion Sebastian Vettel, Fernando Alonso and Lewis Hamilton - took to the track in their new respective cars for the first time.
Vettel proved the fastest out of the high-profile trio and duly took third place in a best time of 1:19.297, although McLaren's Hamilton was just under two tenths further back in fourth. In their own way, both teams may be happy with their comparative efforts.
Ferrari star Alonso, meanwhile, had his first morning in the car disrupted by a hydraulics problem which kept him in the Ferrari garage for the best part of two hours.
When he did return to the track, the Spaniard - whose first appearance of the week naturally drew a far larger crowd to the remote Spanish circuit - continued Ferrari's work on data acquisition rather than chasing outright lap times.
Like team-mate Felipe Massa in the previous two days, the Spaniard therefore finished in a low-key position on the timesheets - seventh - although by the end of the day he was beginning to put in some consistent times on the medium Pirelli tyres during some longer runs.
Day three of the test was also notable for the first two crashes of pre-season - the first of which, for French youngster Jules Bianchi, proved particularly costly for him, Force India and Nico Hulkenberg.
Hulkenberg had been due to get his first run in the car this afternoon but reserve driver Bianchi's side-on crash into the barriers on the exit of turn five after just two laps - which brought out the day's first red flag inside the first hour - forced Force India to spend the next few hours working on repairs. They eventually had to admit defeat for the day, however, as they needed replacement parts to be shipped in from their factory in the UK. Hulkenberg will therefore have to wait until Friday to get his preparations for his return to race action in 2012 properly underway.
Towards the end of the afternoon's running, another reserve driver - this time new Caterham signing Giedo van der Garde - had a smaller off which required his CT01 to be taken back to the pits on a truck, although his car escaped damage.
Meanwhile, Toro Rosso continued their promising start to pre-season with Jean-Eric Vergne taking a competitive fifth place on his debut ahead of fellow young gun Sergio Perez - who was delayed by drivetrain trouble on his Sauber.
Bruno Senna made his testing debut for Williams in their new Renault-powered FW34 and while the Brazilian ended up over three seconds off the ultimate pace, the Grove team stressed via Twitter that "there is a lot of working [sic] going on today so it's not all about going for flat out laptimes."
More encouragingly for the Brazilian and his team was that the car ran trouble-free for a mammoth 125 laps.
Day three times:1) Rosberg* 1:17.613 118 laps
2) Grosjean 1:18.419 117 laps
3) Vettel 1:19.297 96 laps
4) Hamilton 1:19.464 80 laps
5) Vergne 1:19.734 79 laps
6) Perez 1:19.770 48 laps
7) Alonso 1:20.412 67 laps
8) Senna 1:21.293 125 laps
9) Van der Garde 1:23.324 74 laps
10) Bianchi No time
* 2011 car
