LONDON, England - Williams rolled its 2013 Formula 1 car out of the garage on Feb 19, 2013 - and straight into a dispute over the design of its exhausts.The former champion team was the last to display its 2013 cars but had barely started testing the FW35 before it emerged that the sport's governing body disagreed with its interpretation of the rules.A spokesperson said: "The team spoke with the FIA this morning, which was when they gave us their view. The team is now seeking further clarification and a decision about the design will be made before the first race."PRE-RACE SCRUTINEERINGThe season will start in Australia on March 17; there will be one more four-day test period scheduled for Barcelona after the current one ends on Feb 22.Teams can put all sorts of aerodynamic and technical innovations on their cars during testing; the FIA can only declare them illegal if they are presented for pre-race scrutineering.All teams are constantly seeking advice from the governing body, however, as they search for possible loopholes or seek to deny rivals any suspected advantage.The Caterham team has already drawn critical comment from rivals for its exhaust design; Lotus technical director James Allison said at the previous test that he expected changes before Melbourne.The FIA concern is believed to be over the use of bodywork behind the exhaust exits that harnesses the gases for aerodynamic advantage.The technical debate followed a confident roll-out by Williams, which won with Venezuelan Pastor Maldonado at the Barcelona track in 2012.Technical director Mike Coughlan said: "Given the rule stability over the winter I'm pleased with the gains that we've been able to make with this car. It's a better and more-refined F1 car than the FW34."Founder Frank Williams, his team the second most successful in terms of Constructors' championships (nine), finished eighth in 2012 but he saw 2013 as a step forward."Williams has been at the top many times over the last 30 years. It's the nature of the sport to have ups and downs but when we are down we always fight our way back. I'm hoping that with the team we have in place we will be in a position to challenge the very best."The team said more than 80% of the car was new, including the gearbox, rear suspension, radiators, floor, exhausts, bodywork and nose. "Considerable" amount of weight had been shed.Reliability work over the winter had been promising, the gearbox completing 3200km on a dynomometer.