Interior trim restoration?

[Chev malibu]

I am sure some of you must have had that oxidized interior plastic trim, from long term sun exposure. I can scratch it with my fingernail, and peel off a layer of this dull dry rough plastic. It is beyond any plastic detail type spray products. The colour has actually faded from a dark blue, to a grey. I did buy some automotive plastic paint, thinking I could just spray a fresh coat of colour, but the surface needs to be prepped. ( Funny thing is the soft Vinyl interior parts, seat sides, door, and rear seat trim look great still.)

Anybody have ideas on what I can do with this hard plastic trim, or paint prep ideas? None of it is cracked, or what I hope, beyond repair.

Thanks, Bill