Not getting anal about anything. You just say that components will be better but, you can't explain why. I just get bored of all the misinformation that gets spouted on here !
Just to point out though, if you move the tweeters too far away from the mid range woofers, you'll have issues with time alignment. And if what you say is true, how come Kef, use tweeters in the middle of the woofer, in their Uni Q range ?
To get the best sound stage, you should have the speakers at equal distances away from your ears. Obviously in a car, this is difficult so, you should place the tweeters in the footwells, pointing up at your ears.
The footwells are generally the best places to use as, they are generally at equal distances, or very near to, away from your ears, when in the drivers seat. And, the tweeters will be very close to the mid woofers so, the frequency range that each produces, will get you your ear at almost the same time.
Where you're stating you should put the tweeters, will actually be worse, it terms of sound stage, than having co-axial speakers in the door as, they'll be at un-equal distances from your ears and, because the tweeter and woofer are so far apart, the sound each produces, will reach your ears a different times. Therefore, making the sound quality worse ! ;-)