Sportscar driver Lorenzo Trefethen raced in front of his Northern California wine-country fans last week at Sonoma Raceway. Two rounds of the 2015 Pirelli World Championship ran at Sonoma, Calif., on Saturday and Sunday. In race 1, Trefethen, driving the No. 13 ANSA Motorsports/Trefethen Family Vineyards/BRM Chronographes/750 Group/PitStop Furniture/Durango Operating Porsche, was hoping and going for a podium finish. He took a very competitive start on his home racetrack and was running in third place. Later in the race, while running in fourth place, he had a close, unexpected encounter with a GTA-class Mercedes driver, forcing Trefethen to pit and change tires. He finished sixth in the first of the two races. In race 2, Trefethen who qualified fourth for the race, had a slow, standing start and raced really hard to finish fourth. It was a good performance from the Napa-resident racer, but a little disappointing, since his direct competitor for third place in the 2015 Pirelli World Challenge (GT-Cup) championship finished ahead of him twice at Sonoma, grabbing important points from Trefethen. Trefethen is still ranked third, after 17 rounds, and before the season finale race at Mazda Raceway Laguna Seca next week. The Laguna Seca final race will be exciting for ANSA Motorsports and Trefethen; everyone wants to finish on a high note and on the podium. On Wednesday, Aug. 26, ANSA Motorsports visited the Trefethen winery, located in the Oak Knoll district of Napa. The winery organized an open house for employees and club members to tour the winery, meet the team and see, up close and personal, the No. 13 Porsche and Trefethen, who hosted the guests throughout the afternoon. The accomplished Verizon IndyCar Series team, Schmidt Peterson Motorsports, and the award-winning Napa Valley winery, Trefethen Family Vineyards, have partnered for the upcoming 2015 GoPro Grand Prix of Sonoma. Trefethen Family Vineyards’ logo was displayed on the No. 5 Arrow Electronics Honda Indy car, driven at the 2015 IndyCar season finale, GoPro Grand Prix of Sonoma, by the multiple Verizon IndyCar Series race winner: Australian Ryan Briscoe. After a great showing, Briscoe, driving the Arrow/Lucas Oil/Trefethen Family Vineyards/Schmidt Peterson Honda, finished fifth at Sonoma -- his best result of the season. Pirelli World Challenge rounds 16 & 17 telecast is scheduled for Sept. 6 at 2 p.m. EDT on CBS Sports Network. The season finale at Mazda Raceway Laguna Seca in Monterey, Calif., is scheduled for Sept. 10-13.