Yes, car amplifier tuning can help reduce distortion. Cars and trucks come in all different sizes and shapes, so a car stereo needs to be adjusted to sound its best in the environment it is installed. Tuning an amplifier and stereo simply means adjusting the various controls until it produces the sound you enjoy. Bass, treble, fading and balance are just a few of the controls that can be adjusted. As these controls are adjusted and tuned, the distortion levels should decrease. When the sound has been adjusted to your particular tastes, the tuning is complete. Different types of music will require a re-tuning of the stereo system.
For more info, see Troubleshooting Amplifier Problems