The Big G

Coming in Patch 11.1.

Doesn't actually seem like anything too special under the hood, but just wait until those goblins next door see you pull up for the next pool party.

Riding Requirements:

Level 10
Apprentice Riding (ground)
Expert Riding (flying)

Source:

Chrome King Gallywix in Liberation of Undermine (Mythic).

Notes:

This unique mechsuit drops from Chrome King Gallywix in the Liberation of Undermine raid on Mythic difficulty only. It is a guaranteed drop while the raid is current and after that he should continue to drop 3 per kill until The War Within ends.

Travel Mode:

Ground (+60% or +100% speed)
Flying (+150%, +280% or +310% speed)

Speed depends on your riding skill.

More info on Wowhead:

The Big G taught by Keys to the Big G