All 25 teams entered in Sunday's race participated in a test session at Sonoma. Chip Ganassi Racing drivers Dario Franchitti and Dixon topped the time sheets. Franchitti, the four-time series champion, made a lap around this 2.385-mile, 12-turn road course in 1 minute, 18.2945 seconds. Dixon's best lap came in at 1:18.3694.
A Ganassi driver has won the last four IndyCar races. Dixon claimed the victory in the inaugural event at Pocono and then scored a sweep in the weekend doubleheader in Toronto. Charlie Kimball is coming off his first career IndyCar win on Aug. 4 at Mid-Ohio.
Franchitti has turned his season around with top-four finishes in the previous four races. He has moved up to sixth in points (-111). Franchitti started the season with back-to-back 25th-place finishes at St. Petersburg, Fla. and Birmingham, Ala. He also placed 23rd in the Indianapolis 500.
"It's nice to show the results that we've deserved," Franchitti said. "Earlier this year when we did have fast cars, we weren't getting the results. We've managed to turn it around a bit. Recently, we've had the form to get that first win of the season. Sonoma is as good a place as any to try and get that done."
Franchitti has finished no worse than eighth in his seven races at Sonoma. He won here in 2009.
Sonoma has been one of Will Power's best tracks in IndyCar. Power won at this course consecutively from 2010-11. Last year, he finished second to Ryan Briscoe, who was his Team Penske teammate at the time. Power also has won the pole here in each of the last three years.
"Sonoma is definitely a good chance for us," Power said. "It's a track I've had a lot of success on. Although the competition has definitely heated up this year, we still expect to be running right at the front."
Power is 11th in the point standings after finishing second in the series championship the past three seasons. He has not won a race since April 2012 in Sao Paulo, Brazil. Power is hopeful of a win this year and plans to help Castroneves, his teammate, in his efforts to win the title.
"It would be really nice to get a win before the end of the year," Power said. "As far as Helio goes, he's in a very good spot to win the championship, and as a team, we'll be doing everything possible to make that happen."
Castroneves won at Sonoma in 2008.
Briscoe is scheduled to drive the No. 4 car for Panther Racing at Sonoma. He has been behind the wheel of that car in five races this season, finishing no better than 13th. Briscoe fractured his right wrist during an accident in the first Toronto race and was unable to compete in the second event there.
"I'm obviously very happy to be back with the team and in the National Guard car," Briscoe said. "My wrist held up pretty good during the test, although the (wrist) brace was a bit of a nuisance. But we made good progress during the test and worked through our program really well. I was pleased with our pace and definitely looking forward to coming back to find more speed."
Series: IZOD IndyCar. Date: Sunday, Aug. 25. Race: GoPro Grand Prix of Sonoma. Site: Sonoma Raceway Track: 2.385-mile, 12-turn road course. Start Time: 4:30 p.m. ET. Laps: 85. Miles: 202.73. 2012 Winner: Ryan Briscoe. Television: NBC Sports Network. Radio: IMS Radio Network/SIRIUS XM Satellite.