Well, MMDA's stand can be seen in the MMDA Forum. I commented this on Huli Ka! a few days back.
Yikes! Wanted to put a link to the specific thread in the MMDA Forum here but it seems it's down right now. Maybe you can try it later.
Anyway, here's the text from the Huli Ka! post:
There's a thread on the MMDA forum regarding this, and the site administrator (user mmdapublicaffars) has posted a reply saying "BAWAL ang tinted and tampered plate numbers". Now, if there's just some way we can get them to do a public announcement.
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Update: Here's a direct link to the thread. But the site is still down, though.