Try these.
They are sitting on my table waiting to go on Taxi Cabs.
First is in normal fairly bright fluorescent light.
Other two are with all lights off, its a windowless room, with my flash.
One at an angle and one more straight on. Taking a good pic of reflective is difficult.
The black is a 35/35/35/100 CMYK. If I used less "blackness" the black would be more reflective.
Its printed on 3M IJ5100 "white" on a Mimaki printer. YMMV
Note I'm not really trained in printing and color. I know how to cut anything, can print what our designer sends me and kind of understand Pantone Color so If I described something wrong please be gentle.