Prices out here in AZ haven't changed much on diesel - still about $1.35/gal. What I do know is that there was a study done by the city of Phoenix last year that showed that diesel vehicles account for about 30% of the cars and trucks on the road (lots of construction going on out here), but they contribute almost 70% to the airborne particulates. Environmental taskforces haven't lobbied loudly for higher prices that I know of, but I'm sure they have had some effect. Regular gas prices do increase by about $.10-.15 every winter to combat pollution out here - our air is getting as bad as LA's! While the impact of crude oil suppliers can't be denied, I'm wondering if a similar negative view of diesel's effect on the environment may be "fueling" the price increases in other areas?