Wheels and Deals

Women have for decades done 80% of the shopping for themselves and their families, but it's only recently that they've started purchasing the majority of cars. Today, in the U.S., women account for 62% of new-car purchasesyet three-quarters of women buyers plan to bring a man along with them to the dealership, according to a new study by Capital One Auto Finance, America's largest online vehicle lender.

Why are women so hesitant to negotiate on their own? "We teach little girls that we don't like them to be greedy, pushy or overly aggressive," says Sara Laschever, co-author...