This is a great article that outlines the huge influence women have in making purchase decisions, cars inlcuded. Several quotes within the article come directly from Ford excecutives and are based on extensive research by the company. For example:

"Statistics prove...Women are directly responsible for 45 to 50 percent of all new vehicles purchased in the U.S, and they have a direct influence of up to 80 percent of vehicles they don’t purchase ..."

Read the full article here: http://www.webwire.com/ViewPressRel.asp?aId=114359