Rocket League has added item attributes in their newest update, and they promise even more for the future. As stated on their news page:
These attributes include Painted Items which can be used to "paint your wagon," so to speak. Toppers and wheels are the only items that can currently have this attribute. The colours are a little different than the standard blue or white, instead they'll be called "Titanium White" or "Burnt Sienna".
The other attribute is Certified Items. These items track a single statistic while in use. What makes it interesting is apart from the statistic it also has a prestige meter. Every time you reach a certain goal in that statistic - like 50 "Clear Rounds" - the item will get a new prefix. It's like upgrading, but with more grinding rather than dollars.
Rocket League is quite a popular car game, and seems to be a fun title to play for the casual gamer. With promises of more Item Attributes, it should be a very interesting few weeks to look forward to.