Absolutely without question, speakers sitting there in open air, without an enclosure (either a box, or, the ceiling space as a box) will not produce any bass. There has to be a controlled amount of pressure separation between the listening space (the front of the speaker) and the back space behind the speaker. Whether the enclosure is a sealed one or has a tuned port, either way, you need that separation.

Most car speakers work so that the speaker is in some kind of enclosure, or, there is a separation between the inside cabin of the car and the back side of the speakers. For example, on the rear deck your speakers have the back side in the trunk and the front side in the cabin, or in the doors your speakers have the back side as the "outside of the car" (the doors vent to open air) and the front side as the cabin.

Without this, you'll get zero bass response. So your desk test was not valid.

Think of it like this: Have you ever had a situation in your house where you do this?

- Normally when you close an interior door, say, your bedroom door, you are used to how much force to use when swinging it shut.
- But then one day you happen to have the windows in your bedroom open, or perhaps the front door of the house open, or both.
- On that day, you go to close your bedroom door and you just fscking SLAM it inadvertently because you didn't realize that so much less force would be needed to close it.

That's from the pressure differential. As soon as you open up the outside windows the pressure has a place to go and there is no back pressure. Bass on speakers works just like that. If you have a speaker sitting there in open air, there's no back pressure and nothing to "push" against to make low frequency sound waves.

Make sense?