After a combined tally of 26 laps from the first two days of testing in Jerez, Mercedes found itself trailing its rivals in the race to be prepared for round one of the 2013 F1 world championship, but Nico Rosberg
put in hard yards on day three to get it back on track.
The German, who had been limited to just eleven laps by an electrical fire on day one, was back in the cockpit after an equally abortive session for new team-mate Lewis Hamilton, and immediately began racking up the miles as the Three Pointed Star attempted to make up for lost time.
Rosberg's workload, unsurprisingly, focused on reliability to put mileage on mechanical and aerodynamic evaluations, with the team switching between the medium and hard Pirelli tyre compounds throughout. A new front wing design was evaluated during the morning and Rosberg ran with the new parts throughout the afternoon. In total, he completed a marathon 655km – the equivalent of more than two race distances - and exceeded the highest single-day total from last year's Jerez test, set by former team-mate Michael Schumacher in the 2011-spec W02.
“I'm very happy and think it was probably a personal record for me to do almost 150 laps,” Rosberg enthused, “I've never been so well prepared physically as I am this season - I feel on top form and it was no problem to complete the programme.
“To drive the distance from Silverstone to Spa in one day with no problems whatsoever is also a fantastic achievement from the team. It really made up for the last two days and put a smile on everybody's face. In terms of driving the car, I have a good feeling, I can push it and feel comfortable - but obviously we still have plenty of work to do to continue improving.”
Such was the progress being made through the scheduled programme, Rosberg was also able to complete some pit-stop practice during the final hour.
"We were consistent, [and] did everything that we had on the plan,” he confirmed in a later interview with the media, “In fact, we ran out of ideas of what to do because we're limited with tyres. In the end, we were like, 'let's so some pit-stops' and things like that."
The day proved a complete reversal of the first two, and Rosberg is confident that the W04 can be a contender after setting the third fastest time of the week so far.
"I'm struggling a bit with understeer at the moment, but that's what it's about: to highlight what our problems are [and] tell the factory so they can get on top of things ASAP," he concluded, "We've just been unfortunate the last two days. [They were] problems that could have been avoided, but they've also been difficult to fix. It's unusual for relatively small problems. Today showed that we have a very reliable car."
Hamilton returns to the cockpit for the fourth and final day of testing on Friday.