Your car speakers are different from the speakers in your home. Firstly, they are often component or coaxial 2-way systems that are designed to fit in small spaces. Further, they are often have external crossovers and driven to high power levels by dedicated amplifiers. Also, the acoustics within a car create an environment that is not ideal for accurate imaging and sound staging. Further, the fact that you sit closer to one speaker and further from the other creates a time alignment issue that prevents you from being as centrally located as is recommended.
Component and Coaxial
Coaxial speakers are often less efficient and contain greater interference because of having the tweeter mounted inside the woofer. By contrast, having a component system allows you to place the tweeters and woofers separate from one another. This makes the sound ranges work with each car speaker that offer more clear and crisp sound in relation to each other. Coaxial car speaker arrangements tend to be simpler to install, but the clearest audio is almost universally component-based.
A crossover car speaker system can passively or actively separate the frequencies needed for a given sound range to a specific speaker or type of car speaker. Naturally, directing the low range to the tweeters is potentially damaging, and directing the high range to the woofers sounds terrible. By directing energy effectively and even directing the audio range via an active computer controlled crossover, the speaker system is more efficient and the chance of damaging each car speaker is lessened.
To Amplify or Not?
For many types of after market audio systems, amplification is not strictly necessary. However, for the highest volume level and the greatest fidelity to the original sound source, a car speaker system should have an amplifier installed and use that to drive the speakers. The amplifier is used to supply a dedicated amount of power to a type or individual car speaker, and bi-amping can be used to supply separate power to both tweeters and woofers.
Being at the Center of the Sound
Timing alignment slightly delays sound so that you in the driver's seat are at the center of the sound and receive it all clearly. The sound staging and imaging of the audio allows you to feel as if you are actually listening to a live broadcast where every instrument is where it would physically be. When your car speaker system is imaged, you feel as if you are there and the entire listening experience is as lifelike as possible.