The United States Touring Car Championship returned to Sonoma Raceway on July 12 for Round 4 of the 2026 season, with the championship's West Region competitors taking on the demanding 2.5-mile configuration of the Northern California circuit. When the checkered flag flew, GoGoGear.com emerged as the dominant force, scoring victories in both Touring Car and Sportsman while also claiming the E90 Cup class.

The Touring Car battle was headed by Larry Bani, who drove his GoGoGear.com BMW M3 to a convincing class victory. Bani completed 13 laps with a best time of 1:49.305, earning the maximum 100 championship points. His teammate Ali Arsham, sharing a Hyundai Genesis with Gordon Pun, finished second, 11.7 seconds behind Bani. James Bennett-R brought his BMW M3 home third in Touring Car.

The overall pace at Sonoma was particularly impressive in the Sportsman class with Reza Arsham, driving the GoGoGear.com/Konig Wheels Honda Civic, taking the victory. The SP podium was completed by Ken Myers in the I/O Port Racing BMW 330i followed by Michael McColligan in the MC Racing Honda Civic.

The fastest lap of the day belonged to Sam Stowell in the BAF Racing Chevrolet Corvette. Stowell ripped off a 1:47.136, the quickest time shown on the results sheet, but had braking issues and had to retire the car and finished second. Ken Kurtz took the GT class win in the GoGoGear.com/Konig Wheels Hyundai Genesis. Kurtz completed all 13 laps with a best time of 1:51.477, collecting the maximum 100 GT points. Stowell's Corvette was just one of several impressive performances from the GT field, although several GT competitors had technical issues and could not make the start.

Enrique Ferreira took the win in the E90 Cup class in a BMW 328i. Bill Schweitzer-R finished second in another BMW 328i for TNI Racing, and was catching up to Ferreira near the end.