Fuel log template: track every fill and the real L/100 km of each vehicle

Why log fuel vehicle by vehicle

A monthly fuel bill for the whole fleet tells you what you spent, not where it went. Ten vehicles averaging a reasonable figure can hide one that burns far more than it did last quarter. The only reference that means anything for a given vehicle is its own history, on the same kind of routes, with the same kind of load.

Once each vehicle has a baseline, a jump in consumption becomes a question someone can answer. The usual suspects fall into four groups.

• Leaks: a weeping fuel line, a loose filler cap or a damaged tank. Check under the vehicle and around the filler neck.
• Driving style: hard acceleration, long idling to keep the cab warm or cool, sustained high speed. The route may also have changed.
• Fuel that never reached the engine: fills into another vehicle, a jerrycan or a private car. A fill larger than the tank capacity is the clearest sign.
• Maintenance issues: under-inflated tyres, a clogged air filter, worn or dirty injectors, a dragging brake, wheel misalignment. These are the causes a maintenance team can fix, and they often show up in the fuel log before the driver notices anything.

The tank-to-tank method, precisely

The tank-to-tank method, also called full-to-full, measures consumption without a flow meter. You fill the tank to full every time, until the pump nozzle clicks off, and note the odometer at every fill. Because the tank is full before and after, the litres you put in at fill N are exactly the litres the engine burnt since fill N−1.

The first row of the log is the reference fill. Fill to full and note the odometer, but do not count its litres: they replace fuel burnt before the log started. Consumption starts at the second fill.

For averages, do not average the per-fill figures. A short interval would weigh as much as a long one. Divide the total litres, reference fill excluded, by the total distance, and multiply by 100. The same rule applies to the average cost per km.

• Distance of fill N = odometer of fill N − odometer of fill N−1
• Consumption of fill N (L/100 km) = litres of fill N ÷ distance of fill N × 100
• Cost of fill N = litres of fill N × price per litre
• Cost per km of fill N = cost of fill N ÷ distance of fill N
• Average consumption = total litres (reference fill excluded) ÷ total distance × 100
• Average cost per km = total cost (reference fill excluded) ÷ total distance

Pitfalls that ruin a fuel log

A fuel log is only as good as the numbers typed into it. Most strange results come from the data, not from the vehicle, so check these points before you open the bonnet.

• Partial fills. A half fill makes that line look economical and the next one look terrible, because the tank was not full at the start of the next interval. Log it anyway and add a note. The average over a period that starts and ends with a full tank stays correct; only the individual lines are off.
• Missing or guessed odometer readings. A typo of 1,000 km produces a spectacular result either way, and round figures like 50,000 are often estimates. If the reading is missing, leave the cell empty rather than invent one: the next interval simply covers two fills.
• Mixing vehicles. One sheet per vehicle, always. A fuel card shared between two vans, or a fill from a depot tank that nobody writes down, breaks the chain for both.
• Comparing the wrong things. Winter, air conditioning, city routes, towing and heavier loads all raise consumption. Compare a vehicle with its own history on similar work, not with a brochure figure or with a different model.
• Reading one line in isolation. Pumps do not click off at exactly the same level every time. Look at the trend over three to five full fills before drawing a conclusion.
• Mixing units. The template works in litres and kilometres only. Keep every entry in those units.

When consumption jumps: what to check, in order

Start with the data: is the odometer plausible, and was the previous fill really to full? If the line survives that check, look at the context: a new route, a trailer, a heavier load, a new driver. Only then send the vehicle to the workshop, with a clear request: tyre pressures, leaks, air filter, injectors, brakes and alignment.

In FreeMaint, that request becomes a work order on the vehicle, with its history kept on the asset. Work orders, assets and time-based preventive maintenance are part of the free Core tier.

From the spreadsheet to FreeMaint

A spreadsheet per vehicle works for a handful of vans. It stops working when there are twenty files, when nobody consolidates them, and when a consumption jump is noticed but never linked to a maintenance action.

The fuel log is part of the Fleet module on the Business plan, $99 per company per month, flat, never per vehicle or per user. Each fill is entered by hand on the vehicle’s page. FreeMaint is a maintenance system for fleets, not a GPS or telematics tracker: it does not import fuel-card statements or read the odometer automatically. If you already have a tracker, keep it. Cost per km stays in the Excel file; the app shows litres, spend and L/100 km.