It's surprising to me that the "woman driver" stereotype still gets bandied about, even in the most enlightened of car-related forums (which are predominantly male). I cringe whenever the guys talk about "women drivers," but I wonder why the stereotype still exists.
It's probably true that you will see a "soccer mom" type of woman driving full barrel down the Dull3s Toll Road by herself in a huge SUV in the left lane during rush hour. But by the same token, you will probably see as many men driving behemoth SUVs with the same amount of disregard for others. I think it's the type of vehicle more than anything.
Also, I find that men don't share information or discussions about driving techniques or the basic logistics of engine operations, suspension, transmission workings as commonly with women. Car-related discussions and events are often places where guys exercise testorone-related tendencies, be it the "my car has more HP than yours" competitiveness or having the ability to look at scantily-clad women, the latter being the "cars and bikini models go hand-in-hand"—so cars have primarily been the "man's domain." And you can never really improve your skills without improving your knowledge, so if women get excluded by default from these forums, they learn less.
But there are some women that are breaking into the scene. In the professional racing world, there's women like Lisa Kubo, Shawna Marinus, and Leilani Munter. And there are women that are modifying their cars and winning competitions. This tells me that there's nothing inherent in the Y chromosome that results in good driving skills or the ability to understand cars. So why the stereotype?