You'd think it'd be simple, wouldn't you? But black (and white) are about the hardest colors to match; throw in various degrees of semi-gloss, and you've got a real party. It'd probably be easiest to completely repaint all the matte black components to insure they match.

If you're matte black parts are apt to get rough treatment, something like Rustoleum is probably best. Heck, maybe even trunk paint...