Bahrain Test 2, Day 4: Problems galore for F1's big guns as Mercedes end winter on top
Hamilton all-but matches fastest time seen in Bahrain; Merc, Red Bull, Ferrari, Lotus & McLaren all suffer final-day delays; World Champs though complete most single-day mileage of their dismal winter
By James Galloway. Last Updated: 03/03/14 3:49pm
Lewis Hamilton ensured 2014 title favourites Mercedes ended their impressive winter's work on top of the timesheet as F1's most challenging and unpredictable testing season in recent memory came to a problem-filled but dramatic conclusion in Bahrain.
Having already been many pundits' tips for success in the first year of F1's new turbo era before testing commenced at Jerez in January, Mercedes had gradually seen their odds for the season shorten throughout pre-season with the team and Day Four pacesetter Hamilton already installed as favourites for victory at the season-opener in Melbourne and both world titles.
Little is now likely to change in the two weeks before the Australian GP after Hamilton signed off from the winter in style by all-but matching the fastest time seen in Bahrain across the back-to-back tests. His 1:33.278 lap was just two hundredths of a second slower than Felipe Massa's Day Three benchmark for Williams, with both times set on the supersoft tyres.
Hamilton's late-afternoon burst of speed came at the end of an otherwise incident-filled final day for the 11-team field as eight red-flag stoppages meant the winter programme ended in much the same fashion as it started, with all of the grid's heavyweights running into reliability trouble - Mercedes included.
In keeping with the previous seven days of action at Sakhir, principal Renault-powered runners Red Bull and Lotus particularly suffered with a front brake failure on the World Champions' RB10 pitching Sebastian Vettel into a spin and a fire stopping Romain Grosjean's E22 in its tracks a little later.
Sebastian Vettel's otherwise positive day was interrupted by a brake failure
For Lotus, their mid-afternoon stoppage was particularly frustrating as it forced them out of the session with just 32 laps on the board. Having already been dogged by a litany of problems across their self-imposed two-test winter schedule, the early exit meant Lotus finished bottom of the pre-season mileage chart with a meagre 1219km completed. Grosjean, meanwhile, will be the only driver to line up on the Melbourne grid with fewer than 100 laps under his belt this winter.
Quadruple World Champion Vettel will begin his title defence with little more than that in the bag - 162 laps - but the German and his struggling team at least head to the first race on the back of their most productive day with their problematic 2014 car yet.
After seeing their already heavily troubled winter hit a new low on Day Three when the RB10 failed to even complete a full lap, Vettel returned to the track early on Sunday and swiftly reached 20 laps in the opening couple of hours. However, just after midday the 26-year-old was spinning off the circuit at Turn One courtesy of a front-brake failure.
However, unlike Lotus, Red Bull were able to repair the fault and return to the track several hours later and therefore enjoyed a fruitful period of running - eventually ending up with 77 laps on the board.
But the pair were far from alone in running into problems on Day Four, as Mercedes, Ferrari - and most time-consuming of all - McLaren experienced final-day glitches of their own.
For McLaren, whose progress with the MP4-29 appeared to lose some of its early-winter momentum in the second week of Sakhir running, Sunday amounted to just 22 laps with Jenson Button after hours of unspecified delays in their garage.
Mercedes, meanwhile, had already lost the majority of the first four hours of running after a gearbox glitch had to be rectified even before Hamilton completed an installation lap.
Such was the unreliability-filled nature of the final day, that even the previously impregnable Williams FW36 ground to a halt for the first time this winter, the team citing a high-mileage failure of their internal combustion engine.
Nevertheless, that late stoppage couldn't mask what has proved a highly promising winter for the apparently revitalised Williams team as Valtteri Bottas again topped a century of laps and finished with the second-fastest time on the Day Four timesheet, a 1:33.987.
From a quietly efficient start to life with their new Mercedes-powered FW36 back at Jerez in late January, Williams' fastest overall time in Bahrain means they have emerged as more than dark horses for the Melbourne season-opener with the FW36 displaying both impressive pace and, perhaps most crucially of all, reliability.
Alonso was one of many drivers left to wait for a lift back to the pits
Ferrari broke the Mercedes-powered hegemony at the head of the timesheet with Fernando Alonso, despite an afternoon stoppage of his own, clocking the Scuderia's fastest time of the test on 1:34.280 to take third place.
That late improvement placed him ahead of Force India's Nico Hulkenberg - another red-flag culprit - and Toro Rosso's Jean-Eric Vergne.
Sauber, meanwhile, achieved a mileage record for this winter by clocking an astonishing single-day total of 177 laps - 40 laps more than the previous benchmark - as they split their final-day schedule between Adrian Sutil and Esteban Gutierrez.
The two Sauber drivers were split on the timesheet by Marussia's Max Chilton, whose 1:36.835 was a test best for the Banbury team and over one second quicker than perennial rivals Caterham managed all week. They also ended what had been difficult week with a race simulation.