Shifting from gasoline to E85 (85% ethanol fuel, 15% gasoline) may be bad both for your health and air quality.
In the article Effects of Ethanol (E85) versus Gasoline Vehicles on Cancer and Mortality in the United States just published on the Journal Environmental Science and Technology Mark Jacobson reports discusses the potential cancer risk and ozone-related health consequences of a large-scale conversion from gasoline to ethanol.
He finds that

‘E85 (85% ethanol fuel, 15% gasoline) may increase ozone-related mortality, hospitalization, and asthma by about 9% in Los Angeles and 4% in the United States as a whole relative to 100% gasoline. Ozone increases in Los Angeles and the northeast were partially offset by decreases in the southeast. E85 also increased peroxyacetyl nitrate (PAN) in the U.S. but was estimated to cause little change in cancer risk. Due to its ozone effects, future E85 may be a greater overall public health risk than gasoline. However, because of the uncertainty in future emission regulations, it can be concluded with confidence only that E85 is unlikely to improve air quality over future gasoline vehicles. Unburned ethanol emissions from E85 may result in a global-scale source of acetaldehyde larger than that of direct emission.‘

Science Friday 20 April 2007 features an interview with Jakobson.

On ethanol see also Aplia econ-blog post on the impact of the increase of US corn based ethanol production on tortillas’ prices in Mexico.

The Aplia econ-blog has a post on congestion charges.