I've tried, in two different missions, to capture an hovertank alive, but I couldn't.
Both times was against mercenaries.
Both times I enabled savescumming to check if it was possible, I never got the ZZZ icon, but sometimes the hovertank would go down without a death sound.
In the second attempt I downed a tank with a zapper, which deals zero hp damage, the tank went down without making any noise.
I even reloaded to make sure that it would make noise when killed with lethal damage, and it did.
Both missions I got a wrecked hovertank in the loot screen.
Is this specific to mercenary hovertanks? It should be possible to stun hovertanks because there is a disassembly recipe.