Added in Battle for Azeroth Beta Build 25902, https://bfa.wowhead.com/item=156798/ is a new multi-seat flying mount with unique abilities and effects:
|Effect #1||Apply Aura: Control Vehicle|
|Effect #2||Apply Aura: Dummy|
|Effect #3||Apply Aura: Mod Mounted Speed %|
|Effect #4||Apply Aura: Incerase Mounted Speed % - Stacks|
Note: This mount is not available in the game yet, although it's most likely that we'll see it be part of a secret hunt in patch 8.1
Based on the https://bfa.wowhead.com/spell=261396/ spell details, we speculate that the more players join the Hivemind, the faster its movement speed goes, increasing by 10% per person. The buff keeps stacking indefinitely, although https://bfa.wowhead.com/item=156798/ is going to follow "normal vehicle rules" so there might be a limit to how many "seats" there are in the vehicle.
Here's a preview of how the mount is rumored to look like, datamined by Wowhead: