After playing with GRIN's motor simulator, I'm thinking the difference in efficiency won't be nearly so large as you're predicting. It appears that the MAC will actually have an edge in efficiency while getting up to speed, and in some hill-climb scenarios, while the Leaf motor pulls ahead in cruise, but only slightly. I'll get regen braking with the Leaf motor, which may make up for the difference in efficiency in a stop and go "city" drive cycle.
Climbing a hill WOT:
48km/h cruise:
