Or like the myth that Apple computers cost more than Windows based computers, the myth that the suburbs are cheaper than the cities is busted.
There has been a recent uptick in articles I have seen about how cities - specifically urban density - is a good thing and sustainable. Because if your city can support a higher density then the residents don't have to drive as much, which reduces traffic and transportation costs, and makes for a generally happier population. Duh...
See:
3P: Study Finds Transportation Costs Make Most of America “Unaffordable”
FastCompany: The Hidden Cost of Living in the Suburbs: Transportation
TH: Each New Highway Built Drains a City's Population by 18%
HowWeDrive: Live Dense or Die