Fuel Savings Calculator – Compare Two Cars

Todd Mitchell (photo)
By Todd Mitchell
On: Sunday, June 7, 2026 10:24 PM
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Fuel Savings Calculator

Compare the annual fuel bill of two cars side-by-side — instantly see how much you save by choosing the efficient option.

Fuel Savings Comparison

Two cars · One clear winner

Car A: Annual Cost
Car B: Annual Cost
Annual Savings (B vs A)

How It Works

Each car's annual fuel cost is calculated from annual distance, fuel economy, and price. The difference gives the potential annual saving from choosing the more economical vehicle.

Annual Cost = Annual km × (L/100km ÷ 100) × Price/L | Savings = Car A Cost − Car B Cost

How to Use This Calculator

  1. Enter Car A's fuel economy (your current car or option A).
  2. Enter Car B's fuel economy (the alternative).
  3. Enter the current fuel price per litre.
  4. Enter your typical annual driving distance.
  5. Click Calculate — the cheaper car and annual saving appear.

Worked Example

Example: Car A at 12 L/100km vs Car B at 7 L/100km. 15 000 km/year, $1.65/L → A costs $2 970/yr, B costs $1 732/yr → Save $1 238/year with Car B.

Reference Table

L/100km15 000 km @$1.50/L15 000 km @$1.80/L15 000 km @$2.10/L
5.0$1,125$1,350$1,575
7.0$1,575$1,890$2,205
9.0$2,025$2,430$2,835
11.0$2,475$2,970$3,465
13.0$2,925$3,510$4,095
15.0$3,375$4,050$4,725

Frequently Asked Questions

How many years until a fuel-efficient car pays back its higher price?

Divide the price premium by the annual fuel saving. E.g. if an efficient car costs $3 000 more but saves $1 000/year in fuel, payback is 3 years. Use our Break-Even Calculator for this exact calculation.

What annual distance should I use for the comparison?

The average driver covers 12 000–20 000 km/year depending on country. Use your odometer: subtract last year's reading from current reading, or check your insurance renewal which often lists annual mileage.

Does fuel economy change over a car's lifetime?

Fuel economy typically worsens 1–2% per year as engines age, injectors foul, and tyres wear. Over 10 years a car may use 10–20% more fuel than its original rating.

Should I factor in the price difference between petrol and diesel?

Yes — diesel often costs more per litre but diesel engines are 15–30% more efficient. Use the actual pump prices for each fuel type to get an accurate comparison.