I assume your transportation costs take into account the availability of carsharing, which can save more than reducing vehicle miles traveled, but also the number of cars in the household fleet.

Unfortunately, we have not yet gotten municipalities to base their property-tax rates on _both_ the value of one’s abode as well as the value of one’s wheels, as is/was the case for a couple Washington DC-area towns.

Or better, start an on-line index to indicate what it costs the municipality to service the occupants at each address. It would be useful seeing that the properties with the lowest taxes are often the ones that require the most municipal services.