JEREZ DE LA FRONTERA, Spain (AFP) - The first four days of testing for the 2015 Formula One season in Jerez are over with a further eight days to come in Barcelona ahead of the season opening Australian Grand Prix in Melbourne on March 15.
Here, AFP sports looks at what can be learned from the first test.
Mercedes in the driving seat
The double world champions had little to improve on from last year after winning 16 of 19 Grand Prix and were streets ahead again at Jerez when it came to clocking up mileage.
Red Bull team principal described Nico Rosberg's world record 157-lap opening day as "taking the mickey" and despite a couple of spins and stoppages, Mercedes were literally miles ahead with 516 laps over the four days.
The hope is that improvement from the other teams will close the gap, but even if they do, Mercedes are still strong favourites for another double title tilt.
Fast Ferrari
Ferrari were left in Mercedes' dust last season with just one podium finish. However, there were positive signs in Jerez as the SF15-T topped the timesheets on three of the four days with four-time world champion Sebastian Vettel now on board.
Even on the day the famous red car wasn't on top, there was a silver lining as the Ferrari-powered Sauber was fastest on Tuesday and showed impressive speed and reliability all week.
McLaren-Honda needs time
Having joined forces with Honda for the first time in 22 years, McLaren are at the embryonic stage most of the teams were at this time last year when a series of technical rules changes led to widespread problems in Jerez.
That was reflected in time on the track as Fernando Alonso and Jenson Button logged the fewest number of laps of any team with just 79.
McLaren racing director Eric Boullier said the team had only run about 50 per cent of the mileage they had hopes for in Jerez and that any more setbacks in Barcelona will delay their ability to compete for points once the season proper gets under way.
Red Bull sick of Jerez
Red Bull came into Jerez last year on the back of four consecutive double world championship triumphs and proceeded to stall and splutter their way to just 21 laps over four days.
A total of 165 this time in their camouflaged RB11 wasn't quite as bad, although some of those were done without a front wing after Daniil Kyvat damaged the only one they had brought with them on day two.
But given they were the best of the rest in 2014 with Daniel Ricciardo's three race wins the only non-Mercedes success, the gap remains ominously wide.
Rookies roll
Whilst the likes of Alonso, Button and Ricciardo failed to get the time on track they would have craved, a host of new faces got plenty of much needed experience in their new cars.
The youngest ever driver in Formula One history, Max Verstappen didn't look overawed as he logged 170 laps and even went fourth fastest on Wednesday.
His Toro Rosso teammate Carlos Sainz, showing he has inherited his two-time world rally champion dad's natural feel for car racing, rivalled the Mercedes with over a century of laps the day before.
Meanwhile, Brazilian Felipe Nasr topped the timesheets in the Sauber on Tuesday.
