So I just started to read this tread and I see a lot of questions/speculation about diesel vs. gasoline.
I work at an oil refinery in Houston as a process engineer. I work on a magnaformer unit, basically take strait chain carbons and make aromatics (rings) and then we removed the Benzene and Toluene to sell off to chemical plants (in case you didn't know this also lowers the production costs of gasoline).
As for diesel having more energy than gasoline here is the source
http://en.wikipedia.org/wiki/Gasoline
We can't make enough diesel right now, we only keep up with gasoline demand as it is still a core business, but if we could not be making gas and were able to use that capacity to run diesel, trust me we would.
what else...
1barrel (bbl) = 42 gallons
gasoline has less than 500 ppb (thats parts per billion) sulfur content
diesel has less than 450 ppm (parts per million) sulfur content
ULSD (ultra low sulfur diesel) has less than 8 ppm sulfur content
The EPA is pushing lower Nox and is telling us to remove all benzene from gasoline, and we are expecting that no matter who gets elected that permits will be lowered. All of which will contribute to the margins made per bbl. Especially for some other refineries that are older/behind the technologies that will need to build new equipment to retro-fit older units to keep them legal. (as far as I'm concerned the more stuff done to regulate us = guaranteed job for me)
anything I left out I can look into further, just let me know.