The Big G

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:

This mount is available to all eligible characters on your account.
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.

Introduced in:

Patch 11.1

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