Door enclosure depth?

For proper sound quality, you'd want ALL sound radiating from a single point. This is simply impossible with a real speaker, but you get my drift. People place subs in the trunk because they fit. For real music, I prefer up front bass. I've built enclosures inside center consoles that sounded amazing. One guy I know placed a 10 where the glovebox was in his car (no airbag on this one- unless you count his wife ) and it was stunning- and looked stock. Think about it. You're watching Metallica- does Rob Trujillo play from behind you while the rest of the band plays from the front?