Well, I suppose you're the only one...
I just checked the weapon/hitpoint/armourstats, and the Mechanic squad got 160health (40 health/man), and they're armed with 4x tt-33 pistols, which deal 9 damage with quite low accuracy. However, they got airborne armour, so they'll receive 25% less damage when they're on the move.
I can only imagine that your mate kept his volks moving, which causes the mp40 only do deal 20% of its original damage, combined with the airborne armour from the Mechanics this could result in the volks loosing.
But maybe you were just unlucky... Strange things may happen in CoH from time to time. However, the armourtype is a relict from like 1.00 or so which has been overlooked, we'll make some appropriate changes for them in the next version