I first noticed this trend whilst driving through the US from Saskatchewan to southern Ontario a few weeks ago. I had always remembered diesel being cheaper (and, for that matter, the price always seemed to vary less) than regular gas. Now, diesel is more expensive. I’m wondering if there’s any reason for this, or if it’s just as mysterious as everything else about gas pricing?
According to http://www.theoildrum.com/, it’s because half the refineries down south, plus their supporting infrastructure, got pasted by the hurricanes, so the ones left had to choose whether to make gasoline or diesel, and they chose mostly gasoline to keep the greater part of the US wheels on the roads. Only now will they switch to diesel and heating fuel.
I may be simplifying and misinterpreting this.
Not sure how the upcoming cessation of IEA gasoline shipments from Europe will afffect things… if the existing refineries plus extra imports were required to keep US gasoline prices and supplies near normal, what happens when people start needing more heating fuel?
the fraction used for refining diesel is also in demand in the winter for central heating oil, which keeps the price up.
Gasoline usually drops in price once US motorists have finished the vacation season.
Am I mistaken in thinking that making diesel is a byproduct of making gasoline? There shouldn’t be a “choice” on the part of the refinery. Correct me if I’m wrong.
Here in Bogota, Colombia, the price of gas is more or less $2.50 per gallon. Diesel is more or less $1.50 per gallon. And yes, I too believe that diesel is a by-product of gasoline production.
In the UK diesel is generally more expensive than petrol (gasoline), but since diesel contains more energy than an equivalent volume of petrol, it still works out substantially cheaper per mile.
In fact, given how good turbodiesels are nowadays, one could ask why americans insist on sticking to gas when diesel is so much more economical.
Environmental requirements dictate lower sulfur content of diesel fuel, this means
more refining procedures resulting in higher wholesale prices, etc., etc. The idea that
diesel is a 'byproduct" of gasoline is an archaic concept. The increased number of
interstate trucks in the past generation has increased the demand for diesel. For the
most part this can be attributed to the 'just in time" (JIT) delivery concept of retailers.
JIT saves large corps. from building warehouse space into their retail facilities.
Another culprit in the mix is our inefficient rail system.
We need to draw political attention to the U.S. infrastructure, which would include
correlation between trucking and rail transport, among many other neglected aspects
of the domestic/industrial infrastructure.
See this link: http://users.adelphia.net/~pellett/whydiesel.html
Because our cars won’t run on diesel :wally
As silly and as trite as that may sound, that’s actually a big part of it. For most people in the US, switching entirely to diesel would involve either buying a new car or replacing substantial portions of the engine, neither of which is often a very economical option for many of us.
And then there’s folks like me, who won’t do it because Ford doesn’t make a Diesel Mustang.
Well, you’ve had decades to make the switch - get with the program already. Where’s that can-do attitude we hear so much about? Try one of these 
Maybe Dodge could help out with a diesel Viper - wasn’t it originally made with a cast-aluminium petrol-burning version of an old iron diesel truck engine?
I THINK this is what happens:
You heat the incoming crude oil to one temperature, and light hydrocarbons boil off to become gasoline. You heat the crude to a higher temperature, and heavier hydrocarbons boil off to become diesel fuel. What’s left becomes home heating fuel.
In addition, you can break apart the heavier hydrocarbons (that would otherwise become diesel), so that they become gasoline.
In addition, there are different things that need to be removed and added to the various fuels. My impression is that to change from one fuel to another involves a lot of reconfiguration of the refinery.
So, no, gasoline and diesel-fuel production are mostly mutually-exclusive.
:: a little later ::
I looked on Google and found this: http://science.howstuffworks.com/oil-refining.htm
Looks like the different fractions come off mostly simultaneously, but there still seems to be a lot of processing involved. I’d still say a lot of reconfiguration would be in order to switch outputs.