It does. Just at a very basic level they're reducing the amount of smog-producing particulates and toxins such as benzene in the typical gallon of gas. Obviousl

It does. Just at a very basic level they're reducing the amount of smog-producing particulates and toxins such as benzene in the typical gallon of gas. Obviously, a reduction in those constituents is going to affect their ratios in the combustion products, it's like reducing the number of moles on the left side of a balanced chemical equation. The moles on the right are going to drop because there's less material. California has an interesting history with environmental legislation, as it had a clean air board before the EPA existed: http://en.wikipedia.org/wiki/California_Air_Resources_Board http://en.wikipedia.org/wiki/California_Air_Resources_Board