Factory-installed speakers in cars can also be divided into separate speakers – i.e., physically separated from each other – and coaxial speakers, i.e., bidirectional or even three-directional. In this case, another mid-range driver or even two drivers – one for mid-tones and one for high tones – are added to a large woofer. However, regardless of the system that is operating in a given vehicle, these assemblies are often low power (efficiency), generate medium or low quality sound, and are sometimes simply too few in number or poorly selected and positioned. The effect of the accumulation of such errors regularly manifests itself in a similar way: the system reproduces mainly midtones and is unable to generate selective high and low tones. In such a situation, we can apply two solutions: leave the speakers and correct the aforementioned mistakes, i.e. create conditions in which they can show their potential or look for new riders, if the factory riders clearly demonstrate their small capabilities.

https://procarsoundsecurity.com/blog/top-5-best-car-speakers-for-bass/

When choosing new speakers, it’s worth considering their appropriate diameter – 100mm, 130mm, and 165mm models are now standard. In addition, depending on the model, brand, and installation location, it is necessary to select the mounting distance that has a suitable inner diameter. This, of course, means higher efficiency and at the same time the need for more power, which is solved by the amplifier described above (the power of the radio itself is usually very low).