The complaint, filed Thursday, names Tesla, 21-year-old Micah Zuglian, car club organizer Ethan Garabedian, who operates 9Burgring, and Ambassador Wine Bars LLC, which the filing says hosted the Cars and Coffee gathering. The suit comes nearly three months after the Aug. 30 crash.

According to the lawsuit, Michelle Brooks was driving her Honda SUV to volunteer at church when a Tesla Model Y crossed the double yellow lines and struck her head-on. Brooks, a lifelong Bay Area resident and retired project administrator, suffered a traumatic brain injury, fractured vertebrae and ribs, broken limbs and internal injuries, the complaint states. She previously enjoyed gardening, traveling and community volunteer work but now faces ongoing medical treatment and recovery, according to the filing.

Video obtained after the crash shows the Tesla accelerating through curves and a construction zone on the winding highway, at one point reaching 83 mph. The posted speed limit along parts of that stretch ranges from 35 to 40 mph.

The lawsuit alleges Zuglian was representing Tesla at the event and driving a company-owned Model Y when he offered two photographers a ride to demonstrate the vehicle's performance. It accuses Tesla of negligence, including allowing an unfit driver to operate the vehicle.

The complaint also alleges the event organizers and venue proceeded with the gathering despite warnings from local authorities about potential traffic hazards.

"We had the San Mateo Sheriff show up say, don't have the event. You're going to endanger someone. You had a San Mateo supervisor show up say, don't do this event. And the host did it anyway," said the plaintiff's attorney, Niall McCarthy.

McCarthy also questioned Tesla's decision to participate. "How bad do you need to sell one more car? Do you really need that money so much that you're gonna endanger the lives of everyone on the road by sending an employee and a Tesla car to a race club," he said.

Garabedian, in a September interview, defended the Cars and Coffee gathering as an effort to bring car enthusiasts together and support a local business, not to encourage dangerous driving. He maintained that the driver's actions, rather than the event itself, were responsible for the crash.

"We don't condone any recklessness—or donuts, burnouts, revving, anything," Garabedian said. "We're here to have a safe event."

Garabedian said Tesla participated as a vendor and that a company representative was behind the wheel when the collision happened.

The crash has renewed longstanding concerns about speeding and reckless driving along the mountain highways of San Mateo County. An analysis of California Highway Patrol collision data, accessed through UC Berkeley's Transportation Injury Mapping System, found 21 people were killed and 792 injured in crashes along highways 84, 35 and 9 in the county over a five-year period examined in September. Those figures include crashes involving a range of circumstances and do not establish how many were caused by speeding or street racing.

Residents have repeatedly complained about reckless driving along the narrow, winding roads, with some posting signs reminding motorists that public highways are not racetracks. San Mateo County Supervisor Ray Mueller previously said his office tried to discourage organizers from holding the August event because of traffic safety concerns.

County officials have pursued increased enforcement and roadway improvements. At the time of the September report, the county was also considering additional CHP patrols and exploring whether mountain communities could be included in California's speed-camera pilot program.