What does your work truck really cost per kilometre?

If you search for a fuel cost calculator, most of what you get is built for road trips: type in the distance to the cottage, pick your car, get a dollar figure. That is fine for a holiday. It is the wrong tool if you run a truck for work, because the questions you have are different:

• What does it cost me, in fuel, every time this truck moves a kilometre?
• What does it cost me all-in — fuel, repairs, tires, insurance — per kilometre?
• Is this truck burning more than it should, and is it more than it did last spring?

Those three numbers are what you need to price a trip charge, decide whether a job across town is worth it, or notice a truck that is quietly getting worse. Here is how I work each one out, using nothing but fuel receipts and an odometer.

The two numbers that matter

Litres per 100 km (L/100 km) tells you how thirsty the truck is. Lower is better. It does not care what fuel costs this week, so it is the right number for spotting a problem.

Cost per kilometre tells you what the truck costs to run. It moves with the pump price, and it is the right number for pricing work.

Step 1: Measure L/100 km the full-tank way

The dashboard fuel-economy readout is an estimate. Your receipts are not. The reliable way to measure is “full tank to full tank”:

1. Fill the tank until the pump clicks off. Write down the odometer reading.
2. Drive normally — a real work week, loaded the way you usually load it.
3. Fill up again until it clicks off. Write down the litres on the receipt and the new odometer reading.
4. The litres from that second fill are exactly what you burned since the first one.

Worked example. My first fill is at 84,210 km. The next fill is at 84,742 km and takes 71.3 litres at $1.55 a litre.

• Distance: 84,742 − 84,210 = 532 km
• L/100 km: 71.3 ÷ 532 × 100 = 13.4 L/100 km
• Fuel cost per km: 13.4 ÷ 100 × $1.55 = about $0.21 per km

Two things trip people up here. First, a half fill ruins the measurement, because you do not know how much of the tank you actually used — if you top up part-way, add those litres to the next full-tank reading instead of measuring from it. Second, one tank is a noisy sample. A week of highway driving and a week of idling at job sites will give very different numbers, so look at the average over several fills.

If you want a reference point, Natural Resources Canada publishes official fuel consumption ratings for light-duty vehicles sold in Canada in its fuel consumption ratings search tool (the ratings are explained on its understanding fuel consumption ratings page). NRCan itself notes the ratings come from standard tests and that real-world consumption will vary with how, where and when you drive — and a standard test is not a truck with a loaded box and a trailer. Use them as a rough comparison. The number that matters most is your own truck compared with itself.

Step 2: Get the all-in cost per km

Fuel is usually the biggest cost you see every week, but it is not the whole truck. To price work properly you want every dollar the truck costs, divided by the kilometres it drives. Over a year I add up:

• Fuel
• Repairs and maintenance (oil changes, brakes, shop bills)
• Tires, including seasonal changeovers
• Insurance
• Licence, registration and anything else that is only for the truck

Worked example (one truck, one year, 28,000 km):

Cost	Year	Per km
Fuel	$5,820	$0.21
Repairs & maintenance	$2,140	$0.08
Tires	$1,300	$0.05
Insurance	$3,100	$0.11
Licence & other	$400	$0.01
Total	$12,760	$0.46

These are example figures to show the arithmetic, not averages. Use your own receipts.

So the fuel number said 21 cents a kilometre, but the truck really costs about 46 cents a kilometre to run. That gap is where underpriced trip charges come from. I leave out the truck payment and depreciation here to keep it simple; if you want a true replacement-cost number, add them too.

Step 3: Put the number to work

Pricing a trip. A job 19 km away is a 38 km round trip. At $0.46 a km, the truck alone costs about $17.48 every visit, before your time. If you visit weekly for a season, that adds up fast. It is a fair basis for a travel or trip charge on out-of-the-way jobs.

Comparing trucks. If you run more than one, work the numbers out per truck. Two trucks that look similar on paper can differ a lot per kilometre once repairs are counted, and that is usually the first sign one is due to be replaced.

Catching problems early. Keep your L/100 km per truck over time. When one truck climbs noticeably above its own usual number and stays there for a few fills, I check the simple things first: tire pressure, a dragging brake, extra weight left in the box, more idling than usual, or a change in routes.

Doing this by hand works, but it is the part people drop after a month. This is exactly the bookkeeping I built HSLedger to do: you snap the fuel receipt, it keeps the litres and odometer, and it works out L/100 km and cost per km for each truck.

What the CRA wants you to keep

If you claim vehicle expenses for your business, the Canada Revenue Agency expects a record of business driving. On its motor vehicle records page, it lists a logbook with the date, destination, purpose and number of kilometres for each trip, plus the odometer reading of each vehicle at the start and end of the fiscal period.

The same page describes a simplified option: after one full year of logbook records as a base year, you can use a three-month sample logbook in later years, as long as the results stay within 10% of the base year. Read the page for the details, and ask your accountant how it applies to you.

The good news is that the odometer readings you take at each fill for your cost-per-km numbers make the start-of-year and end-of-year readings easy. They do not replace the trip log, though — you still need the date, destination and purpose for business trips.

Checklist

• Fill to the click-off and write the odometer reading on every fuel receipt.
• Work out L/100 km from full tank to full tank, never from a half fill.
• Average several fills before judging a truck.
• Tag every repair, tire and insurance bill to the truck it belongs to.
• Once a year, divide total truck costs by kilometres for your all-in cost per km.
• Use the all-in figure, not just fuel, when you set trip charges.
• Watch each truck’s L/100 km against its own past numbers.
• Keep the CRA logbook: date, destination, purpose, km, plus start and end odometer readings.