Missed this post completely.
It is possible, but it isnt reliable. Matte paints do not have the solvents to protect from elements. HIGHLY unrecommended.
HOWEVER.... and this is still going to cost some $, but it works.... have your car painted the color you want and have it clearcoated with a couple extra coats of clear. THEN, wetsand it with 1500-2000 grit. BUT, do not buff it afterwards. It will have a sheen, smooth finish, but without the shine. You won't even notice the clearcoat is on it. The downfall of this is, as above, protection will be limited, but not as much. Also, the basecoat will be hazed out a bit from the clear being wetsanded. Can be done though. Years and years ago, we had done this on a an old Willys. Painted it black, the whole works.... and it came out looking like a stealth bomber. It went offroad a lot so it killed the finish fast. A scratch or ding on this finish will create a bigger eye sore than if it were buffed.
I agree though, a black, satin finished VX would be insane looking. I would love to see one. Maybe I will Photochop one.
Gary Noonan
'01 S/C VX / '18 Forester XT