What's the difference between MPG and L/100km?

MPG (Miles Per Gallon) is a measure of efficiency used primarily in the US and UK. A higher number is better (more miles per gallon). L/100km (Liters per 100 kilometers) is used in most other parts of the world. It measures consumption, so a lower number is better (fewer liters to drive 100 km).

Why is my car's actual MPG different from the manufacturer's rating?

Manufacturer (EPA) ratings are achieved in controlled laboratory settings. Real-world factors like driving style (aggressive acceleration, speeding), traffic, weather (cold weather and wind reduce MPG), tire pressure, and using the A/C all contribute to lower actual fuel efficiency.

How can I improve my gas mileage?

You can improve your MPG by: 1. Driving smoothly - avoid hard braking and rapid acceleration. 2. Observing speed limits - efficiency usually drops significantly above 50 mph (80 km/h). 3. Keeping tires properly inflated. 4. Removing unnecessary weight from your car (e.g., roof racks, heavy items in the trunk). 5. Reducing idle time - turn off the engine if you're stopped for more than a minute.

Does using the air conditioner (A/C) affect fuel efficiency?

Yes. Using your car's A/C is the largest auxiliary load on the engine and can reduce fuel efficiency by 5% to 25%, especially on short trips. In hot weather, it's a trade-off between comfort and fuel cost.

Is it more fuel-efficient to drive with windows down or use A/C?

It depends on your speed. At lower speeds (city driving, under 40 mph), open windows create less drag than the A/C compressor, making them the more efficient choice. At highway speeds (above 50 mph), open windows create significant aerodynamic drag, and it is generally more fuel-efficient to use the A/C.

Gas Mileage Calculator - Calculate MPG, L/100km & Trip Cost

Calculate your car's fuel efficiency (MPG or L/100km), trip fuel cost, and cost per mile. A comprehensive tool for drivers and fleet managers to budget expenses.

Full original guide (expanded)

Audit: Complete

Formula (LaTeX) + variables + units

This section shows the formulas used by the calculator engine, plus variable definitions and units.

Formula (extracted LaTeX)

\[', right: '\\]

', right: '\

Formula (extracted LaTeX)

\[\text{MPG} = \frac{\text{Distance (miles)}}{\text{Fuel Used (gallons)}}\]

\text{MPG} = \frac{\text{Distance (miles)}}{\text{Fuel Used (gallons)}}

Formula (extracted LaTeX)

\[\text{Fuel Needed (Gallons)} = \frac{\text{Trip Distance (miles)}}{\text{MPG}}\]

\text{Fuel Needed (Gallons)} = \frac{\text{Trip Distance (miles)}}{\text{MPG}}

Formula (extracted LaTeX)

\[\text{L/100km} = \left( \frac{\text{Fuel Used (liters)}}{\text{Distance (km)}} \right) \times 100\]

\text{L/100km} = \left( \frac{\text{Fuel Used (liters)}}{\text{Distance (km)}} \right) \times 100

Formula (extracted LaTeX)

\[\text{Fuel Needed (Liters)} = \frac{\text{Trip Distance (km)} \times \text{L/100km}}{100}\]

\text{Fuel Needed (Liters)} = \frac{\text{Trip Distance (km)} \times \text{L/100km}}{100}

Formula (extracted LaTeX)

\[\text{Total Cost} = \text{Fuel Needed} \times \text{Price per Unit of Fuel}\]

\text{Total Cost} = \text{Fuel Needed} \times \text{Price per Unit of Fuel}

Formula (extracted text)

$ \text{MPG} = \frac{\text{Distance (miles)}}{\text{Fuel Used (gallons)}} $

Formula (extracted text)

$ \text{Fuel Needed (Gallons)} = \frac{\text{Trip Distance (miles)}}{\text{MPG}} $

Formula (extracted text)

$ \text{L/100km} = \left( \frac{\text{Fuel Used (liters)}}{\text{Distance (km)}} \right) \times 100 $

Formula (extracted text)

$ \text{Fuel Needed (Liters)} = \frac{\text{Trip Distance (km)} \times \text{L/100km}}{100} $

Variables and units

No variables provided in audit spec.

Sources (authoritative):

Home — calcdomain.com · Accessed 2026-01-19
https://calcdomain.com/
Lifestyle Everyday — calcdomain.com · Accessed 2026-01-19
https://calcdomain.com/lifestyle-everyday
Automotive — calcdomain.com · Accessed 2026-01-19
https://calcdomain.com/subcategories/automotive
fueleconomy.gov/feg/how_tested.shtml — fueleconomy.gov · Accessed 2026-01-19
https://www.fueleconomy.gov/feg/how_tested.shtml
Car Depreciation Calculator — calcdomain.com · Accessed 2026-01-19
https://calcdomain.com/car-depreciation
Oil Change Interval Calculator — calcdomain.com · Accessed 2026-01-19
https://calcdomain.com/oil-change

Changelog

Version: 0.1.0-draft
Last code update: 2026-01-19

0.1.0-draft · 2026-01-19

Initial audit spec draft generated from HTML extraction (review required).
Verify formulas match the calculator engine and convert any text-only formulas to LaTeX.
Confirm sources are authoritative and relevant to the calculator methodology.

Verified by Ugo Candido on 2026-01-19
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Formulas

(Formulas preserved from original page content, if present.)

Version 0.1.0-draft

Citations

Add authoritative sources relevant to this calculator (standards bodies, manuals, official docs).

Changelog

0.1.0-draft — 2026-01-19: Initial draft (review required).