I have updated the fuel prices, shortened the data to 1 June 2010 and added a regression line to see the over all trends.
Note the jump in gas prices in Sept 2012 that never went a way. I have been unable to find a good reason for the jump. While gas prices continue to decline, the disparity between CA and US continues. While gas prices are declining, diesel prices are essentially flat. Reader comment on the gas price disparity are most welcome.
You comments are most welcome. Please post your comments here.