The transforming armor bit is tripping me up, can't recall anything exact but the description gives me serious Sectaurs vibes, minus the insect angle. Are you sure there's no mark at all? Maybe under the feet or behind the armor?

omggg this is so familiar! I can’t remember the title but will totally come back if it hits me. Those lyrics are So. Frickin. Familiar.

Actually, I think you’re both off. ‘MASK’ has vehicles but no faces on them, and ‘The Wheeled Warriors’ aka ‘Jayce and the Wheeled Warriors’ was more sci-fi with sentient plants. What OP is describing sounds an awful lot like ‘Thomas the Tank Engine’ meets ‘G.I. Joe’. The one you’re trying …