A few things I see on those pictures you posted can help sell the "plastic" more: -Most important: wear off the surface "texture" (tactile texture, as in the noise in your normalmap) on spots that will see more wear, like corners. Also change the diffuse color, the spec (stronger) and the gloss (sharper). You can tell on…
I like the texture, but i think that the scratches may be a bit noisy, but im not sure if that is the spec or bloom or whatever, would it be possible to see a flat diffuse shot?