In Rendered mode decals won’t show when used on objects with transparent material. Change the transparency to 0 and you’ll see it works:
This is a limitation of the current system.
If you want to get a good decal on your plastic your best approach would be to do a cylindrical mapping, then use the mcqueen image in the basecolor channel and in the opacity channel you’d put a version of the mcqueen image but only the alpha channel saved. Uncheck the repeat icon for both.
I made a video tutorial on this technique some years ago:
(and later reply Emboss a signature on glass - #6 by nathanletwory )