Red Bull

It's a drama close to being a crisis, with the vast contrast between the number of laps recorded by Mercedes (309) and the World Champions (21) laying bare the scale of the team's failure to pass what was ultimately a test of reliability in Jerez. Red Bull have the time and resource to regroup, but they are already playing catch-up from a long way behind.

Nor is the situation easily remedied, because Red Bull's problem is that they have more than one.

On the one hand, as Renault were the first to admit, the ERS unit provided for all of their teams proved troublesome throughout the test and was a major reason why the three Renault teams in attendance managed a cumulative total of just 151 laps over four days.

On the other, it seems as if the ultra-tight packaging around the ultra-slim rear of the RB10 is causing the car to overheat - even on very short runs in the modest temperatures of southern Spain in late January. As such, Christian Horner's assurance "the problems should be solvable for the next test in Bahrain" must be treated with a chilly degree of caution. Adrian Newey has, literally, "gone back to the drawing board" and around-the-clock shifts are in the offing at their Milton Keynes base. This will take a lot of sorting out.

Still, only a fool would write them off. As one paddock observer counselled wisely upon departing Jerez, Red Bull could simply have approached the revolution from a different perspective to the rest by pushing beyond the boundaries to find out the outer limits before scaling back, whereas the rest of the field, judging by the times being set, have opted to make steady increments from a low base.

So much now depends on the results of the Bahrain test - and, before that, Adrian Newey's drawing board.

Mercedes

There was a clear sense of 'mission accomplished' about Mercedes' first week of testing with the W05. The first car to take to the track, the most laps completed and the added, and surprising, bonus of being the first team to complete a race distance. For the team long tipped in many quarters as favourites for 2014, it all served as the powerful statement of intent.

Of course, as with last year, day one wasn't without its headaches when a front-wing failure sent Lewis Hamilton careering into the Turn One barriers. But although Mercedes' new joint team boss Paddy Lowe admitted they had found the breakage "confusing", parts were swiftly flown in from Brackley overnight and a fix put in place so that the W05 could resume running from midday on Day Two. From there, the team didn't look back.

Although Nico Rosberg, who completed the 69-lap race distance and more in the wet conditions of the final day, cautioned that questions of pace had yet to be answered, Hamilton's more emphatic verdict that the test had proved "amazing" and "really fantastic" for Mercedes suggested that the in-house targets the team had for Jerez were passed with flying colours. One note of caution is the the car's weight, but what Red Bull would have given for start like that.

Ferrari

The Scuderia were in bullish mood as they packed up on Friday night, delighted with their progress on track as they put down 1000 relatively trouble-free kilometres on track, "unafraid" of Mercedes' extra mileage and, although they certainly weren't saying so publicly, no doubt relieved and encouraged by Red Bull's travails. All in all, with Kimi Raikkonen's feedback dovetailing with that of Fernando Alonso - the pair, it seems, drive in a familiar way, which will aid the development of the F14 T - and the car's track performance correlating with the results forecast from the wind tunnel - a perennial problem for the Scuderia in recent years - it couldn't have gone much better.

Granted, both Alonso and Raikkonen suffered stoppages, but the car looked good out on track, put in longer stints (30 laps) than anyone bar the Silver Arrow and sounded noticeably 'cleaner' from trackside as it shifted through the gears too. Aesthetics don't count for performance, and the F14 T has yet to be tested at full pace, but the team's satisfaction as they departed for Maranello after a good week's work was entirely justified.

McLaren

Amid all the upheaval in the team's senior management structure, McLaren's failure to even turn a wheel of their new MP4-29 on day one was hardly the kind of reassurance fans needed to show they were poised to bounce back from their disastrous 2013. But, as the Jerez test made abundantly clear, a week is a long time in Formula 1 and by the end of it McLaren were back among the headlines for more positive reasons.

That their 'blocky' rear wishbone design proved the technical talking point of the test - even courting admiring glances from rivals - showed that McLaren's designers had come up with an innovative feature, which appears to assist airflow to the diffuser. It now remains to be seen how the rest of the grid will respond to its appearance. Once on the track on Wednesday, the fact that Jenson Button and the immediately on-it rookie Kevin Magnussen topped the timing charts on consecutive days showed the Mercedes-engine car also had promise, even if, in a week all about mileage, the timesheet was essentially meaningless.

Nonetheless, Button's assessment that there were "no scary things with it" would have come as a relief to all after the year-long travails with the flawed MP4-28. That, combined with the immediate pace of their young protégé (despite a late spin and crash in the drizzly closing stages on Friday) and confirmation of Eric Boullier's appointment to the newly-created role of Racing Director, has given the team reasons for optimism heading to Bahrain.

Force India

The Silverstone team were the first to give us an official glimpse of F1's new look a couple of weeks ago, but with hindsight they were also preserving the modesty of the VJM07. There was, however, no hiding place for the car when it was finally revealed in all its glory on Tuesday morning, with the nose design immediately prompting a mass outbreak of schoolboy sniggering among assembled journalists (see also Toro Rosso).

Appendage aside, it was a quiet week with the car looking okay pace-wise but also breaking down more than once. Sergio Perez and Nico Hulkenberg both gained limited running, with the team's new reserve Daniel Juncadella putting down more mileage than the both of them combined in his debut on Friday. Being in the Mercedes boat will also be seen as beneficial at this particular juncture.

Sauber

'Typically Sauber' would be one way to describe the Hinwil team's first four days of running with the C33. Neither spectacular, nor disastrous, 123 laps put them bang in the middle of the mileage charts with their new Ferrari V6 generally running reliably. The week wasn't without its setbacks though, with both Esteban Gutierrez and new signing Adrian Sutil (twice) dropping the C33 and bringing out red flags.

It appears that Sauber, perhaps more than most, arrived at Jerez with the most basic roll-out version of the 2014 challenger, with the team confirming they would debut a "major aerodynamic package" across the back-to-back Bahrain tests. If the car is as big a handful as some observers have suggested in recent days then it couldn't be bolted on a moment too soon.

Williams

It always looked like a good move, but right now the decision by Williams to switch from Renault to Mercedes power seems inspired. Dropping the apparently bullet-proof PU106A into its FW36 was not without its glitches right at the start of the week and the car also experienced suspension trouble. But improvement came throughout the four days and Felipe Massa was able to top the timeheets on Friday after putting in 86 trouble-free laps.

With no real clue of a competitive order likely to emerge for some time yet - precisely when is anyone's guess, frankly - the suspicion is that Williams will need to come out of the traps quickly in the opening races, the logic being that F1's natural order will assert itself eventually. But with a neat-looking car and Massa talking up their potential, it's been a positive start.

Toro Rosso

Do they represent the flipside of the coin to Williams? It certainly looks that way so far. The Italian team's decision to mark F1's technical revolution by switching to Renault power has not got off to the best of starts, although they had marginally more track time than their cousins Red Bull and it's not beyond the realm of speculation to suggest that their problems could be similar. Looking at the STR9, with its aggressive 'coke bottle'-style rear appearing as tight as the World Champions' RB10, it's difficult not to.

So while Kevin Magnussen came of age 'key of the door'-style down at McLaren, Daniil Kvyat spent most of the week kicking his heels. It was a difficult baptism for the 19-year-old Russian, who completed just nine laps to the 21-year-old Dane's 162 and also stopped out on track three times. Like Red Bull, they'll be working hard to turn things around over the next three weeks.

Marussia

The minnows professed themselves happy with the debut of their MR03 - as well they might, considering the car wasn't even at the track at the start of the week and yet still managed to put in 30 laps (nine more than You Know Who managed) of problem-free running.

While that offered them chance to do little more than an initial exploration of systems and reliability, it did give the wider world a chance to take in the car's sleek lines. The Banbury team's cars have proved reliable in the past and their relationship with Ferrari has started on a positive tack. But will such a good-looking car also be a quicker car?

Caterham

They say that beauty is in the eye of the beholder and it's difficult to remember the appearance of a car in recent seasons which has prompted that saying quite so readily as Caterham's CT05. Might it be the only nose on the grid to actually be improved by an accident? That was the general reaction to its aesthetic qualities last week. But what about a nod of respect in the direction of a team who have dared to be different?

Whether the car has inner beauty remains to be seen because it wasn't the best of weeks for Renault-powered teams. But at least Caterham managed to complete more laps than their counterparts, with Kamui Kobayashi racking up 54 upon his return to F1 action on Friday.

Total laps completed by each team

Mercedes - 309.

Ferrari - 251.

McLaren - 245.

Williams - 175.

Sauber - 163.

Force India - 146.

Caterham - 76.

Toro Rosso - 54.

Marussia - 30.

Red Bull - 21.

Laps completed by each engine manufacturer

Mercedes - 875.

Ferrari - 444.

Renault - 151.

The Sky Sports F1 Online team will be providing live commentary of all three winter tests with live updates from trackside also on Sky Sports News.