Went waaaay down this road in the '90's when I was competing in IASCA sound quality competitions and was sponsored by Sony and Kicker. Component quality IS important, but installation is far more important. Before DSP was widely used in car audio, the key to a good soundstage was getting the distances between the left and right speakers in the front stage closer to the same. Thus, many of the cars went to custom made pods in the kick panels.
This still didn't equalize the distance, but it made a huge step in the right direction. My top end Sony head unit and EQ in 1996 didn't use rca's...it was all fiber optic because electrical noise can be a bigger issue than road noise. Between (fasten your seat belts) playing with phasing of the front stage drivers and a judicious amount of time delay, you could create a wide, deep stage with a center in the middle of your dash. The experience was quite a bit like a really good desktop (nearfield) system with the exception that bass in a car will spoil you for a long time. (flat to below 20hz is not hard to do)
I miss those days, but I don't miss laying upside down under the dash. I'll leave that to younger guys.