Track petrol and LPG separately by recording litres and the amount paid for each fuel, then total spending over the same period and distance. Keep the two litre totals separate. Purchases show cash spending; assessing fuel actually used also requires comparable states of both tanks and a complete record of intervening fills.
What to record
Choose clear start and end dates, and keep actual receipts for both fuels alongside odometer readings. The blank template below is for copying into your own records; it is not an app form. Give every petrol and LPG purchase its own row. If you can establish them reliably, note the state of each tank at the start and end of the period too.
- Start date
- Opening odometer (km)
- End date
- Closing odometer (km)
| Date | Odometer (km) | Fuel type | Litres | Amount paid (€) | Tank state / note |
|---|---|---|---|---|---|
| Total amount paid | |||||
Where a receipt includes coffee, a car wash or other items, enter only the amount paid for fuel after discounts. Two purchases at the same odometer reading add no extra distance. If a receipt or reading is missing, flag the gap instead of entering zero.
How to total spending
Add the amounts paid for petrol and LPG separately within the chosen period. Distance is the closing odometer reading minus the opening reading. It must be positive: if either reading is missing or the difference is invalid, do not calculate €/100 km. Keep the litre totals separate.
Fuel spending per 100 km (€/100 km) = (amount paid for petrol + amount paid for LPG) ÷ distance travelled in the same period (km) × 100.
This allocates purchases over all kilometres driven by the car. It need not equal the cost of fuel consumed on that stretch: some newly bought fuel may remain in a tank, while some fuel used may have been bought earlier. Even comparable tank states alone do not establish the precise monetary cost of fuel consumed.
Before comparing periods
- Have you recorded both fuels and every fill in the period?
- Do purchase dates match the start and end boundaries of the odometer readings?
- Do the amounts cover fuel only, with missing entries clearly flagged?
- Have you considered the state of both tanks at the period boundaries?
Enter LPG litres from receipts in your ledger; if useful, record the gauge position only as a note. If the tank states differ or are unknown, compare recorded payments rather than present the result as an exact measure of fuel consumed. For measuring fuel use separately, see the full-to-full method guide. For a single fuel cost based on consumption, see the 100 km fuel cost guide.
Sources
- EMSD: full-to-full measurement and the fuel consumption formula (undated; accessed 2026-11-03). EMSD describes measuring fuel volume between two full tanks; adding petrol and LPG payments and dividing by distance is the spending calculation used in this guide, not an EMSD method.