SONOMA, Calif. — Jack Baldwin, of Marietta, Ga. posted the fastest time in Friday’s 30-minute GTS practice at Sonoma Raceway, at the Pirelli World Challenge Grand Prix of Sonoma presented by Kia.

Weather conditions were 68 degrees under partly cloudy conditions. Early on, Baldwin, in the No. 73 GTSport Racing/Umphrey’s McGee Porsche Cayman S went to the top of the charts with a 1:43.311, followed by Mark Wilkins, of Toronto, Ont., in the No. 38 PutOnTheBrakes.Org Kinetic Motorsports / Kia Racing Kia Optima with a 1:44.041 and Andrew Aquilante, of Chester Springs, Pa. in the No. 32 Calvert Dynamics/Phoenix Performance Ford Mustang Boss 302 with a 1:44.336

Baldwin soon bettered his time with a 1:42.264 — a time that would prove the fastest in the session. Aquilante ultimately ran a 1:42.921 for second fastest time of the session. Nick Esayian, of San Diego, Calif., in the No. 34 Special Operations Warrior Foundation/Justap/Aston Martin Stephen Cameron Racing Aston Martin Vantage GT4 posted the third fastest time of the session with 1:43.208

Of note, GTS Championship points leader coming into the weekend, Michael Cooper, of Syosset, N.Y. in the No. 10 Blackdog Speed Shop/Chevrolet Z28 posted the eighth fastest time with a 1:44.304.

GTS drivers now get set for the second practice of the day scheduled for 11:45 a.m. Pacific. Follow live timing and scoring at