Zend certified PHP/Magento developer

Replaygain vs have been using mp3gain

I have been using mp3gain to bring all of my tracks to the same volume level.
I then saw that audacity offered a normalization option.

I know that normalization basically brings all tracks to the same peak volume and that if there are louder parts to a track its harder to distinguish
Whereas replaygain increases the full track equally.

My question is

Is one better than the other?
Should both be used together? If so, in which order?

I started using these solutions because when listening in the car I kept having to adjust the volume from track to track

I’m looking for the best option to make sure that I can select a column level and leave it