I'm of the mind that you can't teach a woman anything about car maintenance. They figure there will always be a man around to help them with what may be wrong...two or three thousand dollars later.
My best advice to you guys is to occasionally get behind the wheel of your wife/gf's vehicle and drive it yourself. In fact, drive it like you would when test driving a car. Find the typical female faults that come with automobile ailments - anything from brakes to tire pressure. Then, if you can torch the cel phone from her ear and dismiss the "deer-in-the-headlights" look you'll get when you tell her she's driving on borrowed time, firmly place your checkbook in one of your hands and the holy rosary in the other hand, and essentially hope for the best.
BTW: if Wayne's reading this, I already have publishing dibs on "101 Projects for Explaining Automobile Care to a Woman."