And is there any negative effects?

Ur The Australian, via Counting Cats in Zanzibar:

Saudi Arabia is the only country to deny women the right to drive. But despite renewed protests against the ban this year, resistance to change remains strong among conservative royals and clerics.

A report this week by Kamal Subhi, a former professor at King Fahd University, warned that allowing women to drive would provoke a surge in prostitution, pornography, homosexuality and divorce. Within 10 years of the ban being lifted, it warned, there would be "no more virgins" in the kingdom.

Där Ali G sammanfattat situationen perfekt:

(Direktlänk)