You are dead on about the diesel trucks. One of my very best friends bought a brand new 2011 loaded out duramax. A very nice truck that was bought with cash and drove it for 4 months and when it never got better than 13.5 mpg he had enough and ripped all the exhaust, factory ecu, injectors, and put on all the after market race stuff, and now averages 26. I wounder if the EPA has figured out what creates more actual pollution. The diesel trucks getting 26 mpg's or the drilling Riggs and refineries having to produce double the amount for each vehicle? I don't know the answer.
Sorry it took awhile to respond.....
For talking purposes, let's use California as an example, because they have done a lot of work on their effort to implement cap-and-trade and the Low Carbon Fuel Standard (which was just struck down recently by a Federal judge as a violation of the Commerce clause, as CA sought to regulate ethanol outside its borders)....
Table A in the following link shows that it takes about 274,000 BTU of energy to make 1,000,000 BTU of ultra-low sulfur diesel from an average California crude.
http://www.arb.ca.gov/fuels/lcfs/022709lcfs_ulsd.pdf
BTW - from the GREET pathway document for Brazilian sugar cane ethanol, it takes 1,250,000 BTU to make 1,000,000 BTU of fuel, so 5X more energy than it takes to make the same amount of diesel from a contained energy standpoint.....
The Government of the State of California identified diesel exhaust in 1998 as a toxic air pollutant (
http://arb.ca.gov/research/diesel/diesel-health.htm), so they mandate "clean diesel", which
evidently reduces fuel mileage... Their priority is to protect the health of the residents of their State (and I can't blame them if their research correctly points to a link between diesel exhaust and the outcomes that they observe)...... so the lesser of the two evils to them is to mandate clean diesel, even though mileage suffers and the operator of the diesel vehicle sees higher fuel costs.....
Finally the GREET pathway shows that it takes about 1,700,000 BTU to make 1,000,000 BTU of corn ethanol (the stuff that is blended now in your gas). Brazilian sugar cane ethanol is a little harder to make and so it is a "second-generation" bio-fuel.... not available on a wide-spread basis at the current time.....
BTW II - there is about 127,464 BTU in a gallon of diesel, 113,300 BTU in a gallon of gasoline (before ethanol addition) and something like 76,330 BTU in a gallon of corn ethanol.... which explains why you have to run so much more ethanol through an engine to get the same energy output (or mileage)...
Now you have the data when someone tells you that corn ethanol takes so much more energy to make than gasoline - it's true!!!!!
One last point - diesel trucks likely produce more PM2.5 (2.5 micron particulate matter - the stuff that the State of California doesn't like) than the fuel burned in the refineries and on the drilling rigs to power the refining and crude production processes, so to answer the original question you could say that diesels are more "polluting" than the entire fuels production value chain on an equivalent energy basis from the PM2.5 and CO2 emissions standpoint, but IMO pollution is a term used quite loosely these days..... taken to its logical extremes one could say that every human on the planet pollutes the atmosphere with the CO2 that we exhale........