So what accounts for the fact that in CA, diesel costs more than regular,
whereas in other states it costs less ? A refinery shortage (which certainly
exists), would affect everyone evenly.

You can find any number of theories about this that are quite damning
to the powers that be, but the most plausible one seems to be this is
a seasonal thing. Every summer, diesel costs less than unleaded.
Every winter, as northern heaters fire up with fuel oil (basically the
same as diesel), demand goes up and so do prices. If it makes you
feel better, diesel here in TX is costing about the same as premium
unleaded (more than "regular"). It's nationwide. Now, it may be that
you will still pay more in CA after the prices go down here, and I
can't offer any special insight there. Except to say that the filthy
garbage fuel sold in this country as #2 diesel has caused people who
should be in favor of efficient diesel technology to demonize it and
attempt to legisate it out of existence.

All points in favor of biodiesel, IMO. Locally produced,
clean-burning, biodegradeable, CO2-neutral, farm-grown fuel that
lubricates the engine better and keeps it cleaner internally. What's
not to like? (easier said in TX, I grant you, since we have little or
no concerns about fuel gelling in cold weather).

keith