Useful art therapy at Coloring-for-Kids.com: Coloring Page – A Dark Gray Police Car is an online game and printable coloring book that never ends. Coloring trains perseverance, attention to small details, teaches you to bring the work you have started to the end. The young artist will definitely share with you the creative successes of the finished masterpiece! Creative Commons Attribution-NonCommercial 4.0 License. Author of the work: Persimmons Studio.