About car audio's bit?

Recently i bought a car audio system....its cool...but.... in other car's", from out side i can only hear the bit.. not the song... But in my car i can hear both sound and bit..if i increase the volume to max(or closer).. the sounds become hazy and tered....i tryed all of my equalizers... but. there's no change... Is it because that my audio sys is not that up to date... or is it more up to date... HELP ME