The women have been identified by the California Highway Patrol as Sara Elizabeth Pezzimenti, 21, of Palo Alto, and Kelly Marie Ruiz, 26, of Santa Clara.
Pezzimenti attended Palo Alto High School and Middle College and was the daughter of Frank and Robin Pezzimenti. Ruiz was the daughter of a Palo Alto Police Department community services officer, according to Sgt. Sandra Brown.
The two women died when they were ejected from the car, which crashed through a guard rail from the San Ysidro Road overpass at U.S. Highway 101 and plunged onto the highway about 2:15 a.m.
The driver of the car, Beau James Robertson, 29, of Palo Alto, was initially reported Sunday as being in critical condition with life-threatening injuries. But his condition was upgraded to "fair" as of Monday evening, according to a nursing supervisor.
He faces charges of felony driving under the influence and felony gross vehicular manslaughter, according to a California Highway Patrol press release.
According to the CHP, Robertson was driving a 2002 red Chevrolet Camaro on a road that parallels U.S. Highway 101 and attempted to make a right turn onto an overpass.
Robertson lost control of the Camaro, which continued eastbound on the north-south-oriented overpass, the CHP reported. The car jumped the curb and sidewalk, knocked out a metal bridge railing and plunged off the overpass onto southbound 101.
It landed on its right side in the left lane, where it was struck by a Honda sedan occupied by a family of five, according to CHP Officer Don Clotworthy.
The Camaro somersaulted, landing in the right lane, while the Honda landed upright near the center divider.
Pezzimenti, riding in the front seat, was thrown out of the Camaro, as was Ruiz, who had been in the back seat. Both were killed immediately.
Robertson suffered head and internal injuries and was taken by ambulance to the Santa Barbara Cottage Hospital.
Two passengers and the driver of the Honda were also taken to the hospital. The driver was admitted with minor injuries. The other two passengers were released at the scene.
Pezzimenti had been in the Santa Barbara area to celebrate a friend's birthday, according to her mother, Robin Pezzimenti.
The car's driver, Robertson, was a good friend to Sara, Robin Pezzimenti said.
"I'm sure he would have never intentionally hurt her. It was an accident, and that's what I hope people remember," she said.
Sara grew up in Palo Alto and attended local schools. She had a brother, Michael, now 27.
Standing in front of a dining-room table covered with photos of her daughter with friends and family, Robin described her daughter as exuberant, full of life and always on the go.
"If she came home from work at 11 p.m., then she was ready to meet a friend at 11:30 p.m., or she was taking a test online, or she was ready to write a paper," she said of her daughter, a Foothill College student.
"She has a lot of friends (and) touched a lot of people," Pezzimenti said, gesturing to pictures of Sara dressed up as Marilyn Monroe on Halloween or laughing with her grandfather as a little girl.
She had just celebrated her 21st birthday on Sept. 27 with a party in Las Vegas, Pezzimenti said.
Sara had been living at home while studying psychology at Foothill. She worked at Buca di Beppo.
"From the time she was young she was very free-spirited and she was always doing her own thing," Pezzimenti said. "That's what she was doing in Santa Barbara."
"She was always rooting for the underdog, very opinionated and a real fighter," she said, adding that Sara "wanted to do something for social justice" after graduation.
"All I can tell you is she's absolutely the best daughter a mother could have. I loved her tremendously. She was very special," Pezzimenti said. "She was just a beautiful, beautiful child. Everybody loved her. There isn't a person who didn't love her.
"I just don't understand."