Diesel fuel cost per mile

Every figure on this page uses a stated reference efficiency of 6.5 miles per gallon, a plain mid-fleet figure for a loaded Class 8 truck. It is a fixed reference for comparing weeks, not an estimate of any particular truck; a rig running 7.5 mpg spends about 13% less per mile than the reference, one at 5.5 mpg about 18% more. The 500-mile haul line is the same math over one round figure of distance: about 77 gallons burned.

What one mile per gallon is worth this week

At $6.199 a gallon (week of Oct 5, 2026), a truck getting 6.0 mpg spends 103.3 cents a mile on fuel and one getting 7.0 mpg spends 88.6 cents, a gap of 14.7 cents a mile. That is $73.79 on a 500-mile haul and about $14,700 over 100,000 miles ($103,300 of fuel against $88,600). A year earlier, at $3.711 (week of Oct 6, 2025), the same one-mile-per-gallon gap was worth about $8,900 over 100,000 miles. The table above runs the same price from 5.5 to 8.0 mpg.

Where a mile of diesel costs the most

For the week of Oct 5, 2026, California had the highest fuel cost per mile of the 10 regional breakouts EIA publishes, 124.3 cents at $8.082 a gallon, and Lower Atlantic (PADD 1C) the lowest, 87.7 cents at $5.699. At the same 6.5 mpg reference that is $183.31 of fuel on a 500-mile haul, before the truck itself makes any difference. The breakouts overlap: the East Coast figure contains its three subregions and the West Coast figure contains California. Each region's page charts its price against the US average.

What the figure leaves out

This is fuel only. The American Transportation Research Institute's 2026 update of its operational costs study (published July 2026) put the average cost of running a truck in 2025 at $2.336 a mile, $1.854 of it excluding fuel, so fuel came to about 48.2 cents a mile, roughly a fifth of the total. That was a year when the DOE number averaged $3.660 a gallon; this week's $6.199 is $2.539 a gallon above that average.

Fuel also burns on empty miles, which earn nothing; ATRI's 2026 update found deadhead mileage still elevated. If 15 of every 100 miles run empty, fuel per paid mile is the per-mile figure divided by 0.85: 112.2 cents at this week's 6.5 mpg figure instead of 95.4. The arithmetic behind every number on this page is laid out step by step in Cost per mile: fuel math for an owner-operator.

The underlying price is EIA's Monday on-highway diesel release, the same index on the DOE number page. This page only restates it in the unit an operator actually plans in.