gluing styrene to metal

[Hotwheels]

If you try the epoxy test on scrap as I suggested also scuff the plastic side and the metal side that will be joined together with something like 100 grit sandpaper then apply epoxy. I don't think you could pry them apart, it gives added grip. Same principal used in painting real and model cars and trucks. I have bonded other plastics to metal before on different projects and worked great. Let us know whatever method you go with that works best.