Item Attributes is a new items feature of the upcoming June update for Rocket League. Psyonix has prepared an amazing item system that will allow players to further diversify their rides. The system splits into two parts. The first part is named Painted Items. This type of items will recolor an item with entirely-new pigments. The second part of the new system, Certified Items, allows an item to track a particular statistic from online matches.
Please, refer to the original news if you want to know more details about the upcoming Rocket League update from Psyonix.