Matte I reckon.
Nice thinking... Not sure if too tricky? Don't know much about the process
Matte would be spot on in my opinion - its what makes the Audi alloy
I don't know much either, but from what I understand you'd sand down the whole alloy first, mask the silver bits and apply the grey, bake/ let dry, mask the grey apply the silver, bake, apply gloss to the silver bits and then remove the masking from the matte, or skip the gloss all together - a bit like painting a wall haha it might cost a bit more due to the work involved but it would look out of this world! Im seriously coming around to doing this myself now, but I don't think it would be a worthwhile investment come resale time in 6 months. I would just be throwing cash away