1) Hire some women! Women buyers will, on average, prefer to buy a vehicle from another woman when they can--and women salespeople are awesome. By the way, women salespeople will do a great job with male buyers, too.
2) Smile and understand their power. Lots of women are on their own and earning money these days, and, when in families, women statistically make most of the car-purchasing decisions, anyway--so, if you can pleasantly help women smartly enjoy their vehicle purchase, you will get some of your best sales. And referrals.
3) Sell with polite confidence. Women don't want to buy vehicles from mean or weak people, male or female, which means--no matter your own gender--you'll lose the sale if you are condescending or disrespectful. Or just don't know your product.
**To help be sure I wasn't a total Neanderthal about this, I vetted some of these ideas with Dr. Elizabeth Archuleta, whom I would like to thank. Regardless, though, I take full responsibility for the idea and content of this article.