Variable costs
Variable costs scale with the miles you run — fuel, maintenance, tires, tolls and DEF — and they are the costs a routing or equipment decision can actually change.
Last reviewed · by the Fleetchart team
Fuel dominates, typically the largest single line in a carrier's cost structure. Maintenance and tires are variable but arrive irregularly, so they are best amortized per mile rather than recorded only in the months they occur.
Because variable costs respond to decisions, they are where operational improvement shows up: fuel economy, routing around tolls, and preventative maintenance all move this number.
For example, say a truck runs 10,000 miles in a month at 6.25 mpg. It burns 10,000 ÷ 6.25 = 1,600 gallons, and at $4.00 a gallon fuel costs 1,600 × $4.00 = $6,400. Add $1,200 for maintenance, $400 for tires and $300 for tolls, and variable costs are $6,400 + $1,200 + $400 + $300 = $8,300, or $8,300 ÷ 10,000 = $0.83 a mile.
Now say better driving and less idling lift fuel economy to 6.4 mpg. The truck burns 10,000 ÷ 6.4 = 1,562.5 gallons, which costs $6,250, so the month saves $150. Unlike the truck note, these costs drop when you make better choices, so they are often the first place to win money back.