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Fuel Economy Converter

Convert between different units of fuel economy and efficiency.



Understanding Fuel Economy Units

Fuel economy can be expressed in two ways: distance per volume (like MPG or km/L) or volume per distance (like L/100km). These are inversely related, so conversions require special handling.

Common Units

  • MPG (US): Miles per gallon (US gallon = 3.785 liters)
  • MPG (UK): Miles per gallon (UK gallon = 4.546 liters, ~20% larger)
  • L/100km: Liters per 100 kilometers (used in most countries)
  • km/L: Kilometers per liter (used in some Asian countries)

Reference Fuel Economies

  • Compact car: ~35 MPG (US) / 6.7 L/100km
  • Midsize car: ~30 MPG (US) / 7.8 L/100km
  • SUV: ~25 MPG (US) / 9.4 L/100km
  • Hybrid: ~50 MPG (US) / 4.7 L/100km
  • Electric (equivalent): ~100+ MPGe

Conversion Notes

US vs UK Gallons: The US gallon (3.785L) is smaller than the UK gallon (4.546L). A car rated at 30 MPG (US) would be rated at approximately 36 MPG (UK).

Inverse Relationship: L/100km is inversely proportional to MPG. Lower L/100km means better fuel economy (using less fuel), while higher MPG also means better economy (traveling farther on the same fuel).

Quick Estimation: To roughly convert MPG (US) to L/100km, divide 235 by the MPG value. For example, 30 MPG ≈ 235/30 ≈ 7.8 L/100km.


Regional Differences

  • United States: Uses MPG (US gallons)
  • United Kingdom: Uses MPG (UK gallons)
  • Europe, Australia: Uses L/100km
  • Japan, parts of Asia: Uses km/L

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