Just brainstorming so this may be a completely wrong idea.

If these electric motors are more effecient than running the engines on the
jets for taxi purposes and will save the airlines 'considerable' fuel costs
for the taxi operations, do the electric motors need to be 'installed' on
the jets? How about using these efficient electric motors on the tugs, use
the tugs to push/pull the jet from the gate all the way to the hold short
line while the jet is just idling. Then have the electric tugs 'race' down a
taxiway to take the arrivals back to a gate. This would mean more tugs and
personnel to drive them.

Just an (dumb?) idea....