No doubt. In a previous vehicle I slapped in a pair of Kicker CompVR 6.5" "subwoofers" that purely sucked with midbass frequencies. It muddied up the sound badly. The system sounded better with them off or crossed over below 100~ish Hz.
But, I've also had a different vehicle that I put a pair of Orion XTR 8" subs in the front doors ('85 Toyota 4-Runner with the little triangle vent windows, which leaves clearance for the main door windows to *not* hit the woof when rolled down). In that installation the 8"s in the doors were used as subs, crossed over lightly into low midbass since they were up front with the components and actually added to the stage instead of raping it from behind. I also had a 6.5"/1" component set in kick panels for the full-range. Let me tell you, the results were fantastic.
It took a good bit of work to get the doors as solid and deadened as possible to make woofer enclosures out of them. But, even with a few "leaks" the output was impressive. People's jaws just dropped every time they heard the system for the 1st time.