Check increased fuel consumption by comparing two complete periods for the same car and fuel, each from full tank to full tank, with every intervening fill-up and correct odometer readings. Then compare routes, journey patterns and operating conditions. A higher figure alone does not identify a fault; follow the vehicle manufacturer's guidance for technical checks.
Are the periods comparable?
Use records for the same car and the same fuel in both periods. Each measurement needs a full tank at its starting and ending boundary, with every intervening fill-up and its litres recorded. Check that the odometer readings are correct and the ending reading is higher than the starting one. A missing fill-up or uncertain tank boundary makes the comparison unreliable. The full-to-full measurement guide explains the complete method.
Two-period comparison worksheet
Write the start and end dates in each period cell, and the corresponding odometer readings in kilometres in the next cell. Fill each row only from genuine dated records. A blank worksheet for your own notes; this is not a MyFuel form. It does not save entries or calculate a result.
| Dates start/end | Odometer start/end | Distance (km) | Litres | L/100 km | Complete records? | Route / conditions |
|---|---|---|---|---|---|---|
Distance in kilometres is the ending odometer reading minus the starting reading. For each complete interval separately, calculate L/100 km = included litres ÷ distance in km × 100. Exclude the litres in the starting full fill; include every intermediate fill and the final full fill. Round only the final rate to two decimal places, using a decimal point. Calendar-month purchases and the app's approximate summary cannot replace full-to-full measurements.
What changed between the periods?
Compare the routes you actually drove, the mix of short and long journeys, loads carried and operating conditions you recorded. Keep unknown details marked as unknown. These notes may show why two periods are hard to compare; they do not establish what caused a change in fuel consumption. Where possible, collect another complete period with more similar use before drawing a conclusion.
What to do after comparing
- Missing fill-up, uncertain boundary or invalid distance? Recover the actual record from a receipt or your notes if possible. Otherwise start a new complete interval. Do not guess or treat a blank as zero.
- Complete records but materially different routes or use? Record the difference and obtain a more comparable period. Do not assign a cause from the notes alone.
- Comparable rates show no increase? Do not claim that consumption rose. A higher payment is a separate question; see the fuel cost per 100 km guide.
- Comparable records show higher L/100 km? Retain the records, consult the vehicle manufacturer's guidance and seek qualified inspection when warranted. Records alone cannot identify a fault.
Source
EMSD full-to-full measurement method and L/100 km formula, checked 9 November 2026. The worksheet and decision checklist are this article's editorial synthesis, not an EMSD diagnostic method.