Which gallons
Bought, or burned. Pick one and label it.
Cost per mile
Cost per mile on a gallon you can explain.
A cost-per-mile number that mixes purchased gallons and burned gallons is two answers glued together. I will not do that to look precise.
The sample shows the basis on purpose
On the example week, cost per mile uses 25,890 gallons burned and 172,800 miles at $6.54 a gallon. That is about $0.98 on that engine basis. Card gallons that week were 26,940. They are not the same number.
Those are example figures. Your price and your miles will differ. The rule is the part to copy: say which gallons, then do the division.
What ruins the metric
Counting stolen gallons as burned. Counting a typo on the wrong truck. Counting a dead sensor as zero burn or as full burn. Any of those moves the cost per mile without a real change in the fleet.
After the match, the metric is allowed. Before the match, it is a mood.
What I look for
Say the basis every time
Which miles
The same period, from the GPS or TMS you trust.
Which dollars
The price on those gallons, not a blended memory.
Short answers
Before you book.
No. I will not invent a peer number. I will show your basis clearly.
No. That is an example week at an example price. It is not a target.
Next step
Let's put a basis under the number.
If leadership is managing to a cost per mile nobody can explain, start here.