What i would like to point out is the enclosure is very important, our car front door just kill the bass that it should produce, Of course to let the midbass driver to produce those LFE is almost impossible, but without deadening, put in a good midbass driver will just have a nice midrange especially for female vocal, however midbass range (100-400Hz) is fade. I personally has gone through those phase, change 2 sets of midbass hope for miracle, both the midbass range also fade, the male vocal is less 'weight' due to loss of midbass, and finally solve after i completely deadening my front door (Total 3 layers of that).

Another part is a 12" sub without enclosure is just like a vibrator, it won't produce LFE. Last time i dismantle the sub and test on that.

The phasing part, what i understood was car speaker is not directly facing us like the home/PC speaker, mostly it is facing each other (For front door), especially if the car also consist of rear speaker, the phasing will be more complex. This is why car amp/HU also come with phase adjustment.

But anyway i think this already beyond the budget for many of us, so for bass enhancement of budget speaker, my personally opinion deadening is crucial.

Anyway, i owned a THX certified PC speaker that only consist of 6.5" sub, and now is powered by car amp due to built-in amp is dead.