Car shoppers who thought that the Web would save them from wasting money were kidding themselves. As too many people have found, you can bring along boxes of printouts from car-advice sites, and slick or unscrupulous sellers will argue that the information is outdated or irrelevant.

Mobile apps are the obvious answer, if you’re smart about which ones you choose. The best, like those from Edmunds.com, Kelley Blue Book and Cars.com, stress simplicity and speed, not just beauty.

The Edmunds.com app, for instance, has photos, reviews and data to help shoppers winnow their choices and negotiate. It is free on Apple and Android.

Arguably the most helpful feature is Edmunds.com’s True Market Value, which lists the average selling price for a particular model, in a particular region, adjusted for options. In discussing a fair selling price with a sales representative, it is indispensable.