From the weekly EIA "On-Highway Diesel" report.
Negotiated peg in the rate confirmation — usually $1.10–$1.30.
Result
Fuel surcharge / mile
$0.400
Per-load total
$200.00
FSC = max(0, (3.85 − 1.25) / 6.5) = 0.400 $/mi
How the formula works
Every cent diesel rises above the base peg costs you (1 / MPG) cents per mile. At 6.5 MPG, a $0.10/gal increase = ~1.5¢/mi — multiply by your weekly miles to see the real impact.
Automate this in your TMS
Hayes pulls the EIA diesel index weekly, applies per-customer base pegs, and pushes the right FSC line to every invoice and settlement automatically.