this amazing, and i saw an anime while i was in Japan, it was about some sort of organic Sentient Train and when the zombie apocalypse happened it became "corrupted" and turned into a demonic version of itself. it still functioned normally, it wasn't evil it was just the appearence that changed. i was thinking you might try that next if you're up for it. :)
This collection is glorious. I would love to see a scene with the zombies attacking a convoy of those bad boys. The colors on this one stand out. It is good to see more color and less grey in your work. I think that it helps your excellent detail work to stand out better.