Cars.com's app boasts what seems to be the most-comprehensive database of local dealers' inventories, at least in my neck of the woods. For instance, the app came up with 1,539 new Toyota ( TM) Corollas available for sale within 50 miles of my home -- more than double the 580 new Corollas that Edmunds.com's app listed. The Cars.com app also has a great comparison tool that lets you look head to head at up to three cars actually in dealers' inventories. Most apps allow you only to compare models head to head (such as the Corolla vs. the Honda ( HMC) Civic), but won't show you individual cars. Add in an easy-to-use design and real-world price estimates from Kelley Blue Book and the Cars.com app works great. Its only real weakness is that it lacks a tool for building and pricing the model of your choice with whatever particular options that you want.