> Right, most of the energy is used pushing air out of the way
That's certainly the case once you're at speed (above 20km/hr is about the point where more energy is spent overcoming wind resistenace iirc). But I'm taking about taking off from the lights. Even to get you to 10 km/hr for free (or cheap) would be a bit boost for a commuter.
Right, most of the energy is used pushing air out of the way, which you don't get back from regen. Say you ride half a mile before stopping, the time to accelerate to 20mph is pretty small compared to the time you spend cruising at 20mph pushing all that air out of the way.