I captured an M3 half-track from USF as OKW earlier. It was stuck at half health though and it wouldn't let me repair it any more. Plus, the mechanized HQ engineers only brought it back up to half health if it was damaged so apparently its max health was lower than a full health bar. I captured it by killing the vehicle crew when they were outside instead of knocking out the vehicle if that makes a difference. I only have the default USF commanders so I can't reproduce it, since it's a call-in unit.
Screenshot of said half track at "maximum" health:
Relic Entertainment
cblanco ★ 
보드카 중대 
VonManteuffel 
Heartless Jäger 
