SAKHIR, Bahrain : Williams driver Carlos Sainz expressed frustration on Friday at Formula One's limited pre-season testing and suggested teams should be allowed to trade time in the simulator for track mileage. The Spaniard, now a director of the Grand Prix Drivers' Association (GPDA), told reporters on the final day of testing in Bahrain that he would have liked more laps following his move from Ferrari. Sainz was fastest on Thursday and did a hefty 127 laps but that was his sole full day in