My info is a little out of date (~10 years) but I did a MS thesis on aluminum/carbon fiber composites and holy hell are they impossible to produce. There are so many factors that just make these materials not want to go together (similar for Mg / carbon fiber). I would be really surprised to see any real MMC any time soon.
MMC parts are used in quite a few high performance vehicles today, particularly brake rotors. They're still premium parts, but it's stuff you can get from Ford or Honda on their more limited editions.
I know less about it, but as I understand it they're productionized in aerospace now too, again though, just generally for very high spec and price parts.