Painted and 'Certified' items will come to Rocket League with its June patch. Psyonix has long been teasing changes to the item system, and though it promises more to come, the endless stream of toppers is already looking more interesting.
Painted items are colourful reskins of existing items, starting with toppers and wheels. If you receive a painted item, its colour will be randomly chosen. Psyonix gives the examples of 'Titanium White' and 'Burnt Sienna'. I'm hoping for 'Hopes and Dreams Ash' and 'Division Down Denim'.
Certified items track stats. That is, more interesting stats than are currently tracked by each class of item. For example, a 'Sniper Wizard Hat' tracks long goals, levelling up at milestones to a 'Skillful' or 'Incredible' Sniper Wizard Hat.
Psyonix is leaving it to us to discover the full extent of the trackers and prefixes. The stat-tracking will only work in casual and compeititve games, mind, so there'll be no stat farming in custom matches.