JEREZ, Spain - Sergio Perez failed to make himself fully comfortable on his McLaren test debut on Wednesday (Jan 6 2013) but the Mexican Formula 1 driver was still happier than he had expected to be.The 23-year-old, who has moved from Sauber to replace Lewis Hamilton alongside Jenson Button at the title contenders, found his new “office” full of unfamiliar features and controls to keep him busy."It was much more different than I expected," he said after setting the seventh best-time of the day. "You have to adapt yourself to a different position, a different way to hold the steering wheel, pretty much everything is different from the pedals to the steering wheel. It's pretty much starting from zero."I think we are going in the right direction with an incredible day. I'm more happy than I was expecting.”NEW CAR, GOOD POTENTIALPerez still needed to sort out his seat, "to change some stuff", for comfort but there was plenty of time for that."I need to sort out some things with my seat, with my cockpit to be a little bit more comfortable but even then we managed to do an incredible day with good data for us," he said.He had little doubt that the Mercedes-engined McLaren was a step up from the Ferrari-powered car drove in 2012 and took to three podium finishes including two second places."Since I drove it out of the garage, and doing the first laps, I knew that this car has good potential. We don't know how competitive we are at all but all I can say is that the car feels quite good."I would definitely say that the mechanical grip is good on the car but also the aero. It's a very complete car."