Fuel logbook basics: real MPG, cost per km, and fewer guesswork fills

Dashboard economy figures are useful; a fuel logbook is honest. Trip computers smooth over short journeys, cold starts, and roof boxes. When you log every fill with odometer and volume, you see what the car actually consumed over weeks and seasons.

The habit that makes the math work

Log at or near a full tank when you can. Partial fills are fine — modern apps average across entries — but consistent full fills give the clearest trend line. Each entry needs: date, odometer, litres (or gallons), and total price. Optional: fuel grade, station, trip type (commute vs motorway).

Log fuel with optional odometer and attach a receipt photo or PDF. Each car keeps its own history and stats — charts grow richer as you add more fill-ups and service entries.

What the numbers tell you

• Consumption trend: rising L/100 km or falling MPG may mean tyre pressure, a dragging brake, or engine issues worth checking.
• Cost per distance: combine fuel with other running costs to compare two cars fairly — especially if one uses more fuel but cheaper insurance.
• Seasonal shift: winter fuel and short trips often look worse; summer motorway miles look better. A year of data separates noise from a real problem.

Multi-car households

Logging fuel per vehicle stops the "which car is cheaper to run" debate. Statistics show total spend by month, six months, year, or lifetime — per car or across all cars in your garage. Pro removes vehicle limits when you run more than one car.