Mine has the fine mesh that looks like a window from the bottom. Part of the design it to allow the base to come in from the trunk mounted subwoofer. Maybe some cars are now shipping without the premium sound. No subwoofer no need for the cut out.
I believe the cut out serves another purpose in addition to a bass port (HVAC ventilation through rear trunk vents), although not sure why it needs to be so large. I've seen two examples online of the deck remaining covered and both had premium sound.
Has anyone with the 'old' design with no mesh go to the service centre and gotten one installed?
Possible road noise suppression.
This certainly won't help resolve anything but I just took delivery a midrange M3 built June 2019, and it has no cutout at all.
I mentioned to a friend with a LR AWD M3 that I wasn't convinced my car has the premium sound (it's supposed to - full premium interior) and we started poking around. The software is consistent with premium sound and we confirmed that the subwoofer and amp are in the trunk & active. While looking in the trunk he noticed the solid metal panel in my car (image attached) and described the cutout in his slightly older (I think it was built Feb or Mar 2019) car.
I'm curious how other fresh-off-the-assembly-line cars look. If you recently took delivery do you have the cutout or the solid metal panel?
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While looking in the trunk he noticed the solid metal panel in my car (image attached) and described the cutout in his slightly older (I think it was built Feb or Mar 2019) car.
Hmm, good find. Tempted but have same reservation as you.Found this slick cover for the "roof" of the trunk:
For Tesla Model 3 Car Rear Trunk Soundproof Cotton Mat SoundProof Protective Pad | eBay
If I knew that the vent opening isn't actually required for airflow or other reasons I'd jump on this, since it would probably cut down on noise entering from the trunk significantly ...