You are referring to the color with the name 'auto', this color does not exist. Perhaps you want to use inheritance, perhaps you want to have scores with the same color as your car, but removing the color reference will produce no errors and have the same results.

#page-mod-hotpot-report ul.response li.score {color: auto; list-style-image: url([[pix:i/item]]);}

=>

#page-mod-hotpot-report ul.response li.score {list-style-image: url([[pix:i/item]]);}