No, actually diesel is just taken off the tower at a lower point...diesel, gasoline, lube oil, even asphalt are just a part of crude oil. Gasoline has a lot more processing by a long shot than diesel, even ULSD. I have never really seen any reason for it to be as high as it is... I remember stopping in Tulsa back in 2001 and buying diesel for $0.78 a gallon...and in 2008 it spiked over $5 a gallon on my way to Washington state! - - - Updated - - - At one point it was $0.03 different, $0.87, $0.90, and $0.93...then it was $0.10 between the three for a long time. And then a few years ago it did the "spread", $0.10 for mid-grade and $0.30 for premium!!