Sensitivity measures the amount of sound a speaker produces in relation to the power applied to it. If you have an original factory stereo with low power (typically 10-15 watts RMS per channel or less), speakers with high sensitivity (above 90 dB) will be the best option.
If you have a powerful sound system, such as a car stereo installed later or an external amplifier, consider using speakers with lower sensitivity. With the proper power, they will provide excellent sound quality.
Explanation of the power supported by car speakers – The power capacity indicates how much power (measured in watts) a speaker can handle. If you have a low-power system, your speakers don’t need to handle a lot of power. On the other hand, a system with powerful external amplifiers will require speakers whose power capacity is close to the output power of the amplifiers.
Important Note: The fundamental specification in power capacity is the maximum RMS power, not the peak power. RMS ratings actually measure how much power the speaker can handle continuously, and not just for a short period of time. A speaker with a “up to 50 watts RMS” rating will be a better option for your low-power sound system than one with a “10 to 80 watts RMS” rating.