[MetroMPG]

Sidecar... or trailer. Seriously. Or electric bike with a trailer. You've got some other options besides the car with such a short commute.

And SentraSER is right - a 2 mile one-way commute is about the worst situation for good fuel economy in an internal combustion car in the environment you describe. I missed that important distance detail. The car never really gets up to operating temp (not just the engine coolant).

Neutral gliding with the engine running won't hurt anything, provided it re-engages smoothly when you go back to D (no nasty thunks - which I doubt).