I think the point is that when you're driving (at least in a combustion engine car), the 60-70dB noise floor is so high that it almost doesn't matter how good the speakers are in an ideal silent, soundproof chamber.
You also need microphones to pick up ambient sound and play it back at 180 phase shift ..
There is a reason premium audio car packages cost over 2000$
Car's have it really tough in the audio department. SO many things work against it
I recommend ripping your car apart and putting sound insulation panels everywhere you can! Also replacing your sound system...