Driver Nico Rosberg, 27, has admitted that Mercedes' is not the fastest Formula 1 car in 2012 but insists he is in the running for this year's Drivers' title.The German won the 2012 Chinese GP, his first win in more than 100 races - which was a breakthrough also for Mercedes after a 55-year victory drought.GRANDEES LEADINGRosberg said recently the W03 car was perhaps the fastest overall on the 2012 grid but was he correctly quoted?"No, no. It's not the fastest car," he said in an interview with Marca newspaper, conducted with Rosberg in Spanish. "It's a good car, and in some races it's the fastest, and anyway we're in a good situation. We have to take a small step forward and then, yes, we can fight to win every race."His optimism might raise a few eyebrows but perhaps it shouldn't, given he is only being beaten in the Drivers' standings so far by grandees Fernando Alonso, Mark Webber, Lewis Hamilton and Sebastian Vettel.Why, then, is he not considered a real 2012 championship contender?"Because the others are with teams that have won championships, while I'm with... we are a team that is growing," Rosberg said. "If we can win again then people will start looking at us as contenders."The interviewer pointed out that at a team with multiple title winners Ross Brawn and Michael Schumacher, it was "curious" that Rosberg was the one best poised to succeed now."Curious?" Rosberg answered. "I was sure I could do well with this team, but I'm not happy to be ahead of Michael. He is having much less luck than me. His car has not reached the finish four times this year even though he is driving very well -- better than the other years."'NOW WE'RE INVENTING...'Arguably most importantly for Mercedes, however, is that the former Brawn team is now being once again regarded as a leader in F1 innovation, chiefly because of the novel F-duct system seen in 2012 , but Rosberg insists that there are other "very smart things" on the W03."That's the difference between this year and previous years," he said. "Before we were copying, now we are inventing things that are working very well for us. "Ross is still very smart."So perhaps Mercedes and Rosberg will be fully equipped to win the championship together in 2013?"Perhaps this year," the German smiled again. "We are close; we are very close." Stay with Wheels24 for the Formula 1 weekend.