In reply to:

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Another factor to consider in all of this... the EPA does not rate vehicular pollution on the basis of amount of pollution per gallon of fuel burned, but instead on amount of pollution generated per mile traveled, regardless of amount of fuel consumed. This applies to automobiles, trucks may be different.

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Light Trucks (ie. SUVS) are different - they don't have to meet the rules that cars do - they are exempt from most pollution reduction laws and I am not sure if they even have to publish their pollution figures at all.

This is due to a historical situation in that years ago, before SUVs existed light trucks made up such a small %age of the US vehicle fleet and were used mainly for commercial purposes that congress exempted them from having to meet tough anti-pollution laws aimed at reducing the average level of pollution emitted from the US vehicle fleet.
The carmakers saw this loophole (which they helped engineer anyway) and immediately got SUV's classified as light trucks and here we are today, SUVs are now 25% and growing as a percentage of all new vehicles sold and the average MPG figures for the US vehicle fleet is declining thanks to SUVs and the levels of pollution (average) is no doubt the same or worse due to the lack of pollution controls on SUVs.