The racecars drove across the bridge, an unusual lead-up to this weekend's 500-mile championship race at the Sonoma Raceway.
James Hinchcliffe, Marco Andretti, Josef Newgarden, Will Power and Graham Rajal all drove cars in formation, carrying the championship trophy, partly to promote the race and also to honor driver Justin Wilson.
Wilson died on Monday after debris from another car hit him in the head at Pocono Raceway last weekend.
That loss overshadowed the novelty of Thursday's ride and raised the issue, once again, of enclosed cockpits in open wheel cars.
PHOTOS: IndyCars drive across Golden Gate Bridge
"I think that is the last step for open wheel cars is the driver cockpit," Andretti said.
Drivers tried to keep to the speed limit.
"I wish we could have let lose," Andretti said.
The cars can reach speeds of 240 mph.
"Frankly there's no speedometer in the cars. I cannot confirm nor deny if we were in those limits," Hinchcliffe said.