Both in the fastest lap charts and the total laps count, the Mercedes W06 was a class apart throughout winter testing. Only the size of their advantage over the rest of the field at the start of the 2015 campaign remains in doubt, although there is a widespread expectation that the Silver Arrows will be even further ahead when the new season commences than they were at the end of 2014. The best have just got better.

Whichever way you looked at it, Mercedes impressed. Despite the world champions prioritising reliability over pace throughout the 12 days of running, the W06 was over a second clear of the field in Barcelona on soft tyres. “They are unbelievably quick,” acknowledged Jenson Button. Even more ominously, Nico Rosberg’s lap of 1:22.792 remained the benchmark figure for both Barcelona tests even after Williams and Ferrari, their perceived nearest challengers, bolted on the supersofts.

Hamilton v Rosberg, The Rematch is all set for top billing in 2015. And everyone else will just have to be an observer.

Even if second best may be a second behind, Williams appear to have made tangible process over the winter. Their new car has been enthusiastically endorsed by the team’s drivers and, although it is unlikely to match the W06, the new Williams seems to have a slight edge over the Ferrari and Red Bull. In the anticipated three-way fight to be the best of the rest, the difference between the FW37, the SF15-T and RB11 – some day, an F1 team will surely simply name its new car something like 'Ralf' just for ease of access – may be as little as a couple of tenths. "From a performance point of view, it’s clear that Mercedes is still ahead by quite a way, but right behind there is us, Williams and Red Bull, all very close," summarised Ferrari's Sebastian Vettel.

Whether Williams can maintain their lofty position against the inevitable development onslaught from the two superpowers through the season remains to be seen, however.

The post-Jerez test optimism triggered by Ferrari's unexpectedly fast start to 2015 was steadily tempered through the two Barcelona events as the Scuderia struggled to coax their new car into embarking on heavy-duty runs or produce any outstanding lap times. Race simulations eventually arrived on the last weekend, but even when armed with supersofts, the Ferrari remained half a second shy of the soft-shod Mercedes and fractionally adrift of the Williams.

Until the real deal of Melbourne, it’s a guessing game, but as new boss Maurizio Arrivabene concluded on the final day in Barcelona, “the only thing that is quite certain is that Mercedes is there” whilst pointing wistfully into the distance. They're coming back, but they're not there yet.

To damn Red Bull’s winter with faint praise, at least it was better than last year’s wretched regression. But even the RB11’s disguised livery couldn’t disguise the sense of disappointment which surrounded the former behemoths throughout the winter – and their helplessness. The car's breakdown at the end of the pitlane on the final morning rather encapsulated the team's month in Spain.

And, for now at least, there's not much they can do about it. To critical effect, the Renault engine is believed to be significantly down on power compared to the Mercedes and Ferrari units, rendering the aerodynamic secrets which Red Bull have attempted to camouflage through the winter relatively meaningless. Only when Renault introduce their full engine upgrade ‘tokens’ later in the year may the fallen superpowers be sufficiently equipped to give Mercedes something to think about again.

After a horrible 2014, Lotus appear to be on the road to recovery. Although it's not a coincidence that their return to respectability this winter followed a switch from Renault to Mercedes power, the design improvements made to the E23 shouldn’t be underestimated either. Both Romain Grosjean and Pastor Maldonado have raved about the driveability of their new car after 12 longs months at the wheel of the unpredictable and unstable E22. Points and an appearance in Q3 at Melbourne are realistic targets. But only the team’s accountants are well placed to give comment on their 2015 prospects thereafter.

The glaring contrast between McLaren’s optimism about the MP4-30 and the car’s on-track performances was a running theme through winter testing. No matter how bad things seemed to be – and before Jenson Button put 100 laps under the car’s belt on his penultimate day of running, it was verging on very bad indeed – the team’s self-confidence remained absolute steadfast with both Button and Fernando Alonso, albeit prior to his puzzling crash, adamant the new partnership with Honda will prove victorious. But if testing taught us one thing, it’s that it will take time. The car might look the real deal but viewings were few and far between in both Jerez and Barcelona and the chances of the MP4-30 finishing the Australian GP are as slim as the car’s ‘size zero’ bodywork. The early stages will be tough going, but the team believe they will only become competitive when the European leg of the season begins in May. If they are, then it only takes another small leap of faith to believe they might give the best of the rest – if not Mercedes themselves – a fright before the end of the year.

The Sauber might have reliable performance but does it have pace? Other than when it was waylaid by a persistent gearbox niggle during the middle test, the Sauber’s stamina persistently impressed –- only Mercedes bettered their tally of 5708 km. The C34's speed, though, was an altogether different matter. So while backing the Sauber to reach the chequered flag in Australia is a decent bet, just don’t expect it to get there in a hurry.

Appearances can be deceptive – and none more so than with the 2015 Toro Rosso. The beautiful aesthetics of a car which team boss Franz Tost hailed at birth as the best the team have ever made hasn't dovetailed with its ugly on-track behaviour. Lethargic in the slow corners and erratic in the fast, the Toro Rosso has struck trackside observers throughout winter testing as the least impressive of all the 2015 chargers on display. A massive overhaul, almost amounting to an entirely new car, was introduced for the final test, but that only means the team will travel to Melbourne with a largely unproven package – a tall order for their all-rookie driver line-up of Max Verstappen and Carlos Sainz to take on. Theirs could be an uneven battle, for while Sainz has seemingly struggled, the precociously-talented Verstappen, set to become the youngest driver in F1 history, looks a potential star in the making.

Don’t be fooled by the instant reliability of the VJM08 following the very late debut of the new Force India car halfway through the third and final winter test. Although the team are hopeful that their new upgraded wind tunnel will produce dividends in the second half of the season, the price to be paid for ‘cash-flow issues’ over the winter, which was chiefly responsible for the new car’s belated introduction, will be a rough journey at the start of 2015. But at least they will be along for the ride.

PG