Let's be honest: Unless you buy a car that has an expensive, brand-name factory stereo option, your standard speakers probably aren't going to be anything to write home about. Speaker upgrades are a basic and fundamental way to get your car custom sound system started, and probably the easiest way to get immediate, better audio quality in your vehicle.
You'll want to measure the speakers that came with your car to make sure you buy the right size and shape. For instance, most typical front speakers are four, five or six inches (10, 13 or 15 centimeters) across, while most rear speakers measure 6 by 9 inches (15 by 23 centimeters).
There are two types of speakers to consider: coaxial and component. Coaxial speakers are the cheapest and most common models. They integrate midrange sound by incorporating a woofer (for low range sounds) and a tweeter (for high-pitched sounds) into one unit. These speakers are easier to install, but generally produce lower sound quality. You can put speakers like these into your doors or the rear deck -- the area just below the rear glass -- by swapping them out with the originals.
Component speakers are a set of multiple units -- including both woofers and tweeters -- installed at different locations throughout the car, each one producing its own sounds to give a kind of concert quality to your music. These are typically more expensive than standard car speakers and installing them is often much harder, too. In fact, you may end up needing a jigsaw to cut a hole in your A-pillar (where the front door meets the windshield) to install the tweeters [source: Crutchfield]. Then of course, there's the infamous subwoofer. If you want that throbbing, thumping bass that can be heard (and often felt) from several yards away, you'll want one of these in your car. Subwoofers provide that deep, low-end bass and are often installed in the trunk or rear compartment of the vehicle.
Above all, listen to the speakers you want before you buy them. Do they produce the quality you're searching for? Do they suit the type of music you like? Only you can tell what speakers are best suited to your ears, so take them on a test run before you make your purchase.
Speakers are great, but without a receiver to play music, they don't do much. In the next section, we'll talk about the latest in receiver technology and how today's radios do much more than just play music.