Ryan Briscoe, who suffered a fractured wrist in Race 1 of the Honda Indy Toronto in mid-July, was cleared by INDYCAR to return to the No. 4 National Guard Panther Racing car Aug. 13 for a manufacturer/team test at Sonoma Raceway in preparation for the GoPro Grand Prix of Sonoma on Aug. 25.

Eight teams were at the road course, including Sarah Fisher Hartman Racing with full-season driver Josef Newgarden and Lucas Luhr getting his initial seat time in an IZOD IndyCar Series car. The five-time American Le Mans Series champion has been confirmed to race in Sonoma in the No. 97 Honda-powered car.

Also seeing his first track time was 2012 Japanese Formula 3 champion Ryo Hirakawa in the No. 18 Dale Coyne Racing car. The 19-year-old from Hiroshima, Japan, is 10th in the Super Formula (formerly Formula Nippon) series through four rounds this season, with a best finish of seventh at Twin Ring Motegi and Autopolis in Japan.

A.J. Foyt Racing driver Takuma Sato (15th) and former IZOD IndyCar Series driver Hideki Mutoh (13th) also competed in the season opener in April at Suzuka.

The fifth Super Formula race, scheduled for Aug. 24 in Korea, was canceled, leaving the door open to compete at Sonoma. The next scheduled race is Sept. 29 at Sugo.

Joining them on the track were 2006 race winner Marco Andretti, James Hinchcliffe, Ryan Hunter-Reay and E.J. Viso (Andretti Autosport), Sebastien Bourdais and Sebastian Saavedra (Dragon Racing), Ed Carpenter (Ed Carpenter Racing), Justin Wilson (Dale Coyne Racing) and James Jakes and Graham Rahal (Rahal Letterman Lanigan Racing).

“This is a really important race for us,” said Hunter-Reay, the reigning IZOD IndyCar Series champion who is 65 points behind the front-running Helio Castroneves in the championship chase. “I think we test here more than any other track, and it’s important for us to do well here because so many of our sponsors come to this race. We’ve traditionally really struggled on the permanent road courses, but we’ve made some great headway this season and I think this test will really pay off for us.”

Click it: Event schedule, tickets

Briscoe is the defending race winner at Sonoma -- while with Team Penske -- and has finished in the top five each of the past five visits to the 2.385-mile, 12-turn course. He started on the front row last year next to then-teammate Will Power, who has won the past three poles at the track.

"The test went really well and my wrist held up great," Briscoe said.

Briscoe injured his right wrist when his car made contact with a tire barrier in a multi-car incident in the latter stages of the race on the streets of Exhibition Place. Firestone Indy Lights championship leader Carlos Munoz was the spot starter in the No. 4 car for Race 2 the next afternoon and acquitted himself nicely by advancing seven positions to finish 17th.

Oriol Servia drove the No. 4 car in the most recent event -- the Honda Indy 200 at Mid-Ohio on Aug. 4 (14th place).

This past weekend, Simon Pagenaud of Schmidt Hamilton Motorsports filled in for Briscoe at Level 5 Motorsports for the American Le Mans Series race at Road America. Pagenaud, co-driving with Scott Tucker, won the P2 class.

Briscoe has competed in seven IZOD IndyCar Series races this season, with a best finish of 12th in the Indianapolis 500 with Chip Ganassi Racing. He replaced JR Hildebrand at Panther Racing for the doubleheader race weekend in Detroit the next week.

Hildebrand was confirmed Aug. 13 to drive the No. 98 Barracuda Racing car for the GoPro Grand Prix of Sonoma and the season finale at Auto Club Speedway.