Lewis Hamilton will not gain performance advantage by leaving McLaren for Mercedes, insists Martin Whitmarsh Ross Brawn, heavily involved in the genesis of that car, remained with the team when it became Mercedes in 2010 and it is understood they indicated to Hamilton they are confident of making a major step forward when the rule change arrives. But McLaren are themselves powered by Mercedes engines and, as a result, Whitmarsh does not believe Hamilton will be expecting to have a major performance advantage in 2014. He said: "Lewis knows that we are strong team if you measure us over the short, medium or long-term. We have got a long-standing partnership with Mercedes. If you look at our track record since we have had this relationship with Mercedes, in terms of race wins, podiums etc, we have been pretty successful. We enjoy great relationships with them both in Stuttgart, Brackley and Brixworth. I don't think that is material in this particular issue. Hamilton now heads into the final six races of his McLaren career, starting with Sunday's Japanese Grand Prix at Suzuka, 52 points adrift of Ferrari's Fernando Alonso in the drivers' championship. Despite Hamilton's retirement in Singapore with a gearbox problem, hopes remain high he can secure a second title as McLaren currently have the edge on rivals Red Bull and Ferrari. And Whitmarsh insists McLaren will not be holding back on any new parts or upgrades they can provide the 2008 world champion, despite his impending departure. "Lewis is a McLaren driver, he will be the recipient of the development items that we have for this year's car," said Whitmarsh. He will have every single development for instance in Japan and beyond, every race he'll expect things to his car and we'll be open with him on that and he'll understand it. In that regard, he will be involved in the development at the race circuit, although clearly he won't be involved in the development of next year's car.