A DSP car processor is a device that helps optimize the car's audio system by digitally processing the sound signal. It allows users to adjust various parameters such as equalization, time alignment, and crossover settings to achieve optimal sound quality. A DSP car processor is especially useful when installing aftermarket components such as subwoofers and amplifiers. 

The advantages of using a DSP car processor include improved sound quality, enhanced control over the audio system, and the ability to customize sound settings to personal preferences. Key characteristics to consider when choosing a DSP car processor include the number of channels, processing power, and ease of use.