JEREZ, Spain - Nico Rosberg put in the test lap equivalent of driving across Europe on Feb 7 to dispel any doubts about the new Mercedes Formula 1 cars that he and Lewis Hamilton will be racing in 2013.After two troubled days, with Rosberg able to complete only 14 laps and Hamilton managing just 15 before crashing, the Mercedes showed their reliability once the kinks had been worked out. The W04 ran superbly with Rosberg completing 148 laps of the Jerez test track with barely a break for lunch.'I HAVE A FEW PAINS'By the end he was second on the time sheets with comfortably the most laps covered.Hamilton, back in the car on Feb 8 for the final day of the 2013 test, will be happy to hear it after a brake failure at 260km/h sent him piling into the tyre wall on his first outing with the team.Rosberg, winner at the 2012 Chinese GP with a car that was otherwise uncompetitive for most of year was delighted by the 24-hour turnaround. "I've never been so well prepared for a season as this year," he said, "because I remember in previous years I've always been a bit tired, but today no problem. "I've a few pains here and there,but I'm really on top form, so I'm very pleased. The last two days we were just very unlucky because we had problems that were small things and we were not able to solve them in a day."But today really made up for it. It was fantastic and it really put a smile on everybody's face."RELIABLE MERCThe total distance covered of 655km was more than two race distances and beat the highest single-day total of 132 laps from the 2012 test set by now-retired seven-times champion Michael Schumacher.It was also roughly the same distance as that by road between the British GP circuit and Spa-Francorchamps in Belgium - a feat that was not lost on Rosberg, who rounded off his afternoon with some pit-stop practice.Rosberg said: "It's a fantastic achievement, distance-wise, in one test day with the F1 car with no problem whatsoever, pounding out the laps, being very consistent."Today showed we have a very reliable car. Nothing at all went wrong, not the slightest thing."