LONDON, England - McLaren's 2013 Formula 1 car is being designed with driver Lewis Hamilton in mind, technical director Paddy Lowe has revealed.Media speculation, however, is rife that the team's 2008 World champion is about to sign with Mercedes for 2013.McLaren's Lowe sounded confident that Hamilton would still be alongside Jenson Button in 2013. "That's how we're working in terms of the design for next year," he said. "It is our assumption that they are the drivers we will field next year. We have two fantastic drivers and we are very keen to keep them."'TRUST ME, I WAS HAPPY'Lowe also admitted that whether or not McLaren had to change a driver at relatively short notice was "not a huge issue" in terms of engineering and design.Hamilton, meanwhile, has played down suggestions his foul mood after winning the Italian GP was a sign he is set to quit McLaren.Hamilton said: "We buried my aunt that week, so she was constantly on my mind... it's been a tough time for the family, and (I) just had a lot on my mind."It was nothing to do with being unhappy. Trust me, I was happy." Stay with Wheels24 for the 2012 Singapore F1 GP weekend.