Since the 1970's (at least), lowriders have been an intrinsic part of Latino culture in San Francisco. These souped up, tricked out vintage vehicles, often with fancy hydraulics that make them "dance" down the street, are the subject of the above documentary short by KQED Arts, featuring footage that appears to have been shot at this year's Cesar Chavez Day parade in April (more from that day below).
Lowriders figured into the Frisco Five protests earlier this year in the Mission, ferrying protesters triumphantly down the street after their hunger strike, and the cars are a completely California invention like coming out of Mexican-American neighborhoods in Los Angeles where the tradition of tricking out old cars dates back to the 1940's.
KQED found at least one woman who competes on the lowrider circuit with her own vintage cars, Ruby Ramirez, who's a member of the Califas Bomb Club. She tells the station, "This is where I feel at home, I can be who I want to be." Also, she adds, "You have to be a chingona [translation: badass] when you're rolling with the big boys."
[h/t: Laughing Squid]