Fuel Savings Calculator
Calculate fuel cost for two vehicles from their fuel efficiency (mpg or L/100km), distance driven, and fuel price, and see the savings from the more efficient one.
mi
$
/ gallon
mpg
mpg
Fuel Savings
$630.00
(37.5%)
Vehicle A Fuel Cost
$1,680.00
Vehicle B Fuel Cost
$1,050.00
More Efficient Vehicle
Vehicle B
How Fuel Savings Between Two Vehicles Is Calculated
This calculator compares the fuel cost of two vehicles based on their fuel efficiency, how far you drive, and the price of fuel, so you can see exactly how much choosing the more efficient one saves you in both dollars and percentage terms. It works with either mpg (miles per gallon, higher is better) or L/100km (liters per 100 kilometers, lower is better) — pick whichever unit matches how your vehicles' efficiency is listed.
Fuel Cost (L/100km) = (Distance ÷ 100) × L/100km × Price Per Liter
Example
Driving 12,000 miles a year at $3.50 per gallon, a 25 mpg vehicle costs about $1,680 a year in fuel, while a 40 mpg vehicle costs about $1,050 — a savings of $630, or roughly 37.5%, from choosing the more efficient vehicle.
Common Use Cases
- Deciding between two cars when shopping, factoring in long-term fuel costs.
- Estimating how much a hybrid or more efficient vehicle saves over a gas-heavier one.
- Comparing a current vehicle against a potential replacement before trading in.
- Justifying the upfront cost premium of a more fuel-efficient vehicle over time.
FAQs
Why does a lower L/100km number mean better efficiency?
L/100km measures how much fuel is used to travel a fixed distance, so using less fuel for the same distance is better — the opposite of mpg, where a higher number (more miles per gallon) is better.
Does this account for differences in fuel type?
No — enter the fuel price each vehicle actually uses (regular, premium, or diesel) separately if they differ, since this calculator assumes a single fuel price applies to both vehicles' cost comparison.
Should I use my real-world mileage or the manufacturer's rating?
Real-world fuel economy is often somewhat lower than official manufacturer ratings, especially in city driving or cold weather. Using your own tracked average, if available, gives a more accurate savings estimate than the sticker rating alone.