DETROIT, Mich. – Robert Thorne, of Littleton, Colo., was fastest in a shortened second practice session at Detroit’s Belle Isle and the Cadillac V-Series Challenge presented by the Metro Detroit Cadillac dealers.

Twenty-five of the entered 27 drivers for Rounds 10 and 11 of the GT/GTA Championships took to the 13-turn, 2.3-mile temporary street course for the scheduled 30-minute session – weather was overcast and 78 degrees.

Very early in the session, Thorne, in the No. 6 K-PAX Racing McLaren 650S GT3 set the pace with a 1:32.114, with Nicky Catsburg, of Voorthuizen, Netherlands , in the No. 25 Blancpain Racing Lamborghini Gallardo GT3 FL2 second with a 1:32.153, and Peter Cunningham, of Milwaukee, Wis., in the No. 42 RealTime/Acura Motorsports/HPD Acura TLX-GT in third with a 1:32.271.

Shortly after Thorne set the early fast lap, a full-course yellow occurred with the No. 20 Bentley/Breitling/Mobil 1 Bentley Continental GT3 of Butch Leitzinger, of Rebersburg, Pa. off in turn 13. The removal of the No. 20 car took up the balance of time left in the session. Leitzinger was not injured in the incident.

Bryan Heitkotter, of Fresno, Calif., in the No. 05 Nissan GT Academy GT-R Nissan GT-R GT3 recorded the fastest lap in GTA with a 1:33.106.

Drivers and teams now prepare for Saturday morning’s Round 10 qualifying session scheduled for 7:30 am Eastern. Follow live timing and scoring at