Irish Calculators
Everyday money

Fuel Savings and Vehicle Payback Calculator

Compare fuel spending and other annual running costs for two vehicles travelling the same distance. Payback uses your extra purchase price and positive annual saving, without resale or financing assumptions.

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Your numbers

km
L/100 km
L/100 km
€/L
€/L
€
€
€
Your figures stay on this device.

How the calculation works

This comparison isolates the annual operating-cost difference between two vehicles travelling the same distance. It can then relate a positive annual saving to an additional purchase price, producing simple payback rather than a full ownership valuation.

Annual fuel cost = annual kilometres × litres per 100 km ÷ 100 × price per litre. Savings = current cost − alternative cost. Annual running-cost saving adds the difference in other annual running costs. Simple payback = additional purchase price / positive annual running-cost saving.

  1. Calculate annual fuel use

    Multiply annual distance by each consumption figure and divide by 100. This converts the efficiency measure into litres used over the same driving horizon.

  2. Price each operating scenario

    Multiply litres by the corresponding fuel price, then include the other annual running costs entered for each vehicle. Keep insurance, maintenance and similar items consistently scoped.

  3. Compare saving and extra purchase cost

    Subtract alternative annual costs from current costs. A positive saving can support a simple payback calculation by dividing the extra purchase price by that saving.

Worked example: Lower consumption

Sample inputs demonstrate the method. They are not a forecast or product offer.

The first example covers 10,000 kilometres at 8 versus 5 litres per 100 kilometres, with fuel at 2 per litre. The vehicles use 800 and 500 litres, so the annual fuel-cost difference is 600.

Annual distance (km)
10000
Current consumption (L/100 km)
8
Alternative consumption (L/100 km)
5
Current fuel price (€/L)
2
Alternative fuel price (€/L)
2
Additional purchase price for alternative (€)
0
Current other annual running costs (€)
0
Alternative other annual running costs (€)
0

Expected result

Annual fuel saving
€600.00
Worked example: Equal vehicles

Sample inputs demonstrate the method. They are not a forecast or product offer.

Annual distance (km)
100
Current consumption (L/100 km)
5
Alternative consumption (L/100 km)
5
Current fuel price (€/L)
2
Alternative fuel price (€/L)
2
Additional purchase price for alternative (€)
0
Current other annual running costs (€)
0
Alternative other annual running costs (€)
0

Expected result

Annual fuel saving
€0.00

Understanding your result

Fuel saving and total running-cost saving are separate outputs. An efficiency improvement may be offset by higher insurance or other operating costs.

Simple payback ignores financing, resale-value differences, discounting and changing prices. A negative annual saving does not provide a positive payback period to recover an extra cost.

Questions you might have

What does this fuel savings calculator include?

Compare fuel and running costs for two vehicles, then estimate the time needed to recover an additional purchase price.

Which assumptions should I check?

Use the same annual distance for both vehicles. The simple payback ignores financing, resale-value differences, discounting and changing future prices. Enter other annual running costs consistently; do not include the purchase price again.

Choosing the right inputs

Annual distance
Enter annual kilometres for the same driving requirement in both scenarios. Different distances would combine efficiency changes with a change in travel demand.
Alternative fuel price
Use the alternative vehicle's price per litre when its fuel differs. Each vehicle's consumption is entered in litres per 100 kilometres.
Additional purchase price for alternative
Enter only the additional purchase price of the alternative, not its whole purchase price when comparing it with a current option.

Common mistakes to avoid

  • Do not enter MPG figures in the litres-per-100-kilometres fields.
  • Do not include purchase price again among annual running costs.

Assumptions to check

  • Use the same annual distance for both vehicles. The simple payback ignores financing, resale-value differences, discounting and changing future prices. Enter other annual running costs consistently; do not include the purchase price again.

Sources and method

Read our calculation and testing approach.