How important is the distance between the tweeter and woofer?

My car has only 4”x6” holes for front speakers on the dash. So, I might only be able to install the 1” tweeters there. And for the 5.25” woofers, they would be installed on the drilled holes at the bottom and rearmost of the front doors. The question is, is the distance between tweeter and woofer matter? I know it should be matter in home audio, but I’m not sure for car audio because, in my opinion, car speakers might receive a compromised or more flexible design compared to home audio speakers.
 
Are the mids going to be firing into the sides of the front seats?

Audio is subjective. For some, if the voice coils are not aligned on the same vertical plane, the speakers are garbage. If you're not using single-strand pure silver speaker wire with each individual conductor separated from each other and all walls and floors by precisely 6" and the wires don't have impedance compensation networks on the speaker end, you may as well be listening to the music through tin cans connected by a piece of string.

Others just need good smooth frequency response and good quality components.
 
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Are the mids going to be firing into the sides of the front seats?
Probably, yes. But that point is the factory's location for some cars with an audio upgrade option. It's about a 6" woofer there.

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Is there a different door panel for that car for different stereo options that have a midrange speaker further forward (where the side pocket is in that photo)?

I don't think that there's a DSP or anything else that could get that midrange location to be anything considered Hi-Fi. Good for listening to a golf game or talk radio but not high quality audio.
 
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Is there a different door panel for that car for different stereo options that have a midrange speaker further forward (where the side pocket is in that photo)?
No, they’re the same. Only difference is the presence of the grill, in the red circle. The standard stereo option has speakers on the dash and rear parcel, while the upgraded stereo option receives additional 6” speakers at that point (red circle).
 
4x6 isn't a terribly small hole to find in the dash. You can surely get more than a 1" tweeter in there. Is there not the depth for a 4" co-axial or something?

A lot of car audio guys would go ahead with just the tweeter, but I would really like to see that dash mounted install getting down to 500hz or less. Letting the doors do something more like sub duty.
 
4” + tweeter should be great in the 4x6 openings, have done it before.
Use metal plumbers strap to mount and carefully aim the drivers to reflect off of the windshield. Try and get the rh drivers to target the left ear of the person in the left seat, opposite for the other side…
 
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