Inexpensive portable navigation systems and even cheaper smartphone nav applications are making the pricey in-dash systems offered by automakers less attractive to many consumers. But some people prefer in-dash systems because of their larger screens and because they offer more features. Plus, you never have to worry about forgetting an in-dash system at home. Finally, prices for in-dash systems are starting to drop.

Bluetooth is a wireless technology that allows two compatible devices to communicate. In the car, it lets you operate a mobile phone "hands-free," meaning you don't have to hold the device while making or taking a call or performing such functions as accessing the phone's address book. (Of course, you have to use your hands to operate certain Bluetooth features via the vehicle's controls.)

Automotive sound systems are more complex now that portable media players, hard-disk drives and smartphones are along for the ride. But the basic radio/speaker setup hasn't drastically changed, even though more speakers and more amplifier power have been added over the years.