FYI: The cars that are hidden in this update are going to be unlocked on July 18 (Esper, Masamune, Marauder, Aftershock)
4 features that are coming in this update are the new Quick Chat Options, Ingame spotlights, new Rocket Labs map called Pillars and last but not least: The Trade-in system with the themed map called Neo Tokyo.
Full patchnotes (including the locked content) can be found here
They said be prepared. But OMG this is taking epic proportions. Rocket League is expanding on multiple levels in the game. The new addition to Rocket Labs: Pillars, is yet another feature that is coming in June.
As stated on their website Pillars will be available both on the online and offline exhibition play and will be added to the Rocket Labs playlist. You can be sure that Pillars will be played alot.
More news is coming, so stay tuned!