"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 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.