[madderscience]

if you haven't already, run full synthetic NON-positraction gear oil in these gearboxes (and maybe your main gearbox too). Almost all gear oils have posi additive, which increases friction. I like redline superlight shockproof. It will reduce friction substantially over regular dino gear oil. One caveat is some older geartrains (like my land rover transfer case) can have problems with low sulphur lubricants, so check with the VW community to make sure it won't cause problems first. its literally a pour-in efficiency improvement.

And +1 on ditching the AGMs. Keep your eyes open for a wrecked LEAF and get the battery from that one, reconfigure if needed, and be astounded. (or at least pleased)