Art Deco and decidedly diesel themes seem to crop up in the strangest places. Here's the oddest one I've found.
Note: I am intentionally leaving all dieselpunk/ steampunk themes as seen in Doctor Who and Torchwood out of this post (digging through 40+ years of Whovian lore to make a complete list).
This brings us to... My Little Pony: Friendship is Magic.
The character Rainbow Dash is the best example of a dieselpunk trope appearing out of nowhere, complete with goggles and a love for aviation.
Rainbow Dash's greatest dream is to join Equestria's aerial stunt team, the Wonderbolts. The evil pony villian, Nightmare Moon, preys on Rainbow Dash's desire by tempting her with a spot on the Shadowbolts (aka shadowy gothic Wonderbolts).
Here's the Wonderbolts in all their Art Deco poster glory.
(As can be seen in My Little Pony: Friendship is Magic, Episode 1.)
I just saw that years ago, DC gave all their comics pulp-style covers. You can see how they looked here: