The national average price for a gallon of diesel rose just one-tenth of a cent for the week ending May 7, according to the Energy Information Administration. Prices on a region-by-region basis indicate that instabilities remain, however, as West Coast prices spiked, while other areas fell modestly.

The West Coast posted the highest price jump that week, up 8.2 cents to $3.18. This was followed closely by California, which saw an 8.1-cent rise to $3.244, the highest price in the nation. The region that saw the largest price drop also posted the cheapest diesel: The Gulf Coast region posted a 1.8-cent drop to $2.814.

For more detailed diesel price information, go to www.fleetowner.com/diesel.xls.