PetrolCalculator

Fuel calculator

MPG Improvement Savings Calculator

Estimate annual fuel savings by comparing your current and improved UK MPG.

Use this calculator

Compare your current and improved UK MPG at the same annual mileage.

What your result means

The calculator works out fuel use separately at each MPG before comparing the costs; MPG changes are not treated as linear savings.

Worked example

Example values are illustrative and editable in the calculator.

Current annual cost
£2,213.30
Improved annual cost
£1,721.45

The example saves £491.84 per year.

Formula

Saving=Cost at current MPG−Cost at improved MPG\text{Saving}=\text{Cost at current MPG}-\text{Cost at improved MPG}

Illustrative improved-MPG savings

ScenarioEstimated result
40 improved MPG£276.66
45 improved MPG£491.84
50 improved MPG£663.99
55 improved MPG£804.84

Current versus improved example

ScenarioAnnual litresAnnual cost
35 UK MPG1,558.7 litres£2,213.30
45 UK MPG1,212.3 litres£1,721.45

Improved-MPG sensitivity at 12,000 miles and 142p/litre

Improved MPGAnnual saving
40£276.66
45£491.84
50£663.99
55£804.84

MPG savings are not linear

Fuel consumption is the inverse of MPG, so each MPG increase does not produce the same fuel saving. The calculator works out litres and cost independently at both MPG figures before comparing them.

Assumptions and limitations

  • Fuel-only savings; maintenance savings are not included.
  • Use real-world MPG where possible.

Helpful questions

Is a 10% MPG improvement a 10% fuel saving?

No. The fuel use is calculated separately at both MPG values.

Can I use this for diesel?

Yes. Enter the relevant diesel price and UK MPG.

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