Having been given the green light by FIA official Charlie Whiting after several modifications had been made to the circuit, three teams kicked off the final testing session of 2008 at Jerez, Spain yesterday.
Just BMW Sauber, Williams and Honda were present on Tuesday although everyone else is expected out on track on Wednesday.
The quickest driver of the day was BMW test driver Marko Asmer who completed 79 laps and posted a quickest time of 1:20.189.
Dani Clos, a 19 year old Spaniard, took to the wheel of an F1 car for the first time in a Williams. He managed 75 laps with a fastest time of 1:23.224 as the team tested out their new KERS for the first time.
Mike Conway was out on track for Honda. He could only manage 20 laps and a quickest time of 1:24.123 thanks for a problem with sensor wiring on the car.
Unofficial Times for Day 1 Testing at Jerez
Pos Driver Team Time Laps 1. Asmer BMW-Sauber 1:20.189 79 2. Clos Williams-Toyota 1:23.224 75 3. Conway Honda 1:24.123 20