The campaign's message is that driving should be a woman's choice. The struggle is rooted in the kingdom's hard-line interpretation of Islam known as Wahabbism, with critics warning that women driving could unravel the very fabric of Saudi society.
Though no laws ban women from driving in Saudi Arabia, authorities do not issue them licenses. Women who drove on Saturday had driver's licenses from abroad, activists said.
Activist Aziza Youssef, a professor at King Saud University, and another activist said protest organizers received 13 videos and about 50 phone messages from women showing or claiming they had driven. She said they have no way to verify the messages.
May Al Sawyan, a 32-year-old mother of two and an economic researcher, told The Associated Press that she drove from her home in Riyadh to the grocery store and back. Activists uploaded a four-minute video of her driving to the campaign's YouTube account.
Al Sawyan said she was prepared to be jailed if caught by authorities. She said she was far enough from a police car that she was not spotted.
"I just took a small loop," she said. "I didn't drive for a long way, but it was fine."
Al Sawyan's husband and family waited at home and called her nervously when she arrived at the store to check on her, she said. She drove with a local female television reporter in the car. They were both without male relatives in the vehicle, which in itself defies the country's strict norms requiring women to have a male relative in public.
"I am very happy and proud that there was no reaction against me," Al Sawyan said.
It is not clear if police turned a blind eye to women driving or simply did not see the scattered, quick spins around towns. An AP journalist in Riyadh said there were no roadblocks or checkpoints set up to watch for female drivers. He saw only a few law enforcement vehicles on the road.
A security official said authorities did not arrest or fine any female drivers on Saturday. The official spoke on condition of anonymity because he was not authorized to speak to the media.
Ahead of the protest, authorities offered mixed messages, perhaps cautious not to push too hard against the kingdom's religious establishment. Hard-line clerics say women driving will lead to "licentiousness." A prominent cleric also caused a stir when he said that medical studies show driving a car harms a woman's ovaries.
The ministry that oversees the police warned that violators who "disturb public peace" would be dealt with forcefully. The statement catered to conservatives who saw this as directed at women drivers, but was also interpreted by reformers to be directed at anyone who harasses women drivers.
"This is part of the politics," said Youssef, the activist and professor. "My analysis is that government is doing all this to protect ladies from the harassers."
Saturday's campaign is in stark contrast to the kingdom's first major driving protest in 1990, which saw 50 women arrested. They ultimately had their passports confiscated and lost their jobs.
In June 2011, about 40 women got behind the wheel in several cities in a protest sparked when a woman was arrested after posting a video of herself driving. Later another woman driver was arrested and sentenced to 10 lashes, but the king overturned the sentence.
King Abdullah gradually has introduced reforms since then. The reforms, which include allowing women to sit on the national advisory council and permitting women to vote and run in municipal elections, may have readied the deeply conservative nation for change.
But the stringent male guardian system has been left untouched. It requires women to obtain permission from a male relative to travel, get married, enroll in higher education or undergo surgery in some cases.
Women who complain about not having male relatives to drive them places or money to spend on a driver are told by many Saudi clerics to call for better public transportation systems, not a driver's license.
Karen Elliott House, the author of "On Saudi Arabia: Its People, Past, Religion, Fault Lines," has interviewed many key members of the kingdom's very private royal family and says the monarchy is trying to slowly embrace more openness.
"They try to constantly, like a tight rope walker, to balance by tilting first toward the most rigid clerics and then toward modernizers to keep a balance in the kingdom," House said.
In the days leading up to the campaign, some hard-liners called for women drivers to be harassed. Ultraconservative clerics and top religious scholars, angry that the government is not cracking down harder, protested earlier in the week.
Youssef said she and four other prominent women activists received phone calls from a top official with close links to Interior Minister Prince Mohammed bin Nayef, urging them not to drive on Saturday. She also said that "two suspicious cars" were following her all day.
Despite the obstacles, Youssef said only one woman reported being pulled over by police Saturday.
The woman was asked to sign a statement promising not to drive again and her husband took over the steering wheel, she said.
"We will continue driving and posting videos," Youssef said. "The whole thing is raising awareness and making people get used to us driving as normal."