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MPG to L/100km: Fuel Efficiency Conversion Guide

November 25, 2023 6 min read

Understanding Fuel Efficiency Measurements

Fuel efficiency is measured differently around the world. The United States uses MPG (miles per gallon), while most other countries use L/100km (liters per 100 kilometers). Understanding both systems helps you compare vehicles and calculate fuel costs when traveling internationally.

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Key Difference: Inverse Relationship

Unlike most conversions, MPG and L/100km have an inverse relationship:

  • Higher MPG = Better efficiency (more miles per gallon)
  • Lower L/100km = Better efficiency (less fuel per distance)

Conversion Formulas

MPG to L/100km

L/100km = 235.214 ÷ MPG

L/100km to MPG

MPG = 235.214 ÷ L/100km

Quick Reference Conversion Chart

US MPG to L/100km

  • 10 MPG = 23.5 L/100km (Very Poor)
  • 15 MPG = 15.7 L/100km (Poor)
  • 20 MPG = 11.8 L/100km (Below Average)
  • 25 MPG = 9.4 L/100km (Average)
  • 30 MPG = 7.8 L/100km (Good)
  • 35 MPG = 6.7 L/100km (Very Good)
  • 40 MPG = 5.9 L/100km (Excellent)
  • 50 MPG = 4.7 L/100km (Outstanding)
  • 60 MPG = 3.9 L/100km (Exceptional)

L/100km to US MPG

  • 4 L/100km = 58.8 MPG
  • 5 L/100km = 47.0 MPG
  • 6 L/100km = 39.2 MPG
  • 7 L/100km = 33.6 MPG
  • 8 L/100km = 29.4 MPG
  • 9 L/100km = 26.1 MPG
  • 10 L/100km = 23.5 MPG
  • 12 L/100km = 19.6 MPG
  • 15 L/100km = 15.7 MPG

Example Calculations

Example 1: MPG to L/100km

A car gets 30 MPG. What is this in L/100km?

  • 235.214 ÷ 30 = 7.84 L/100km
  • Result: 7.8 L/100km

Example 2: L/100km to MPG

A European car uses 6 L/100km. What is this in MPG?

  • 235.214 ÷ 6 = 39.2 MPG
  • Result: 39.2 MPG

Vehicle Fuel Efficiency Categories

Passenger Cars

  • Compact/Economy: 30-40 MPG (5.9-7.8 L/100km)
  • Midsize Sedan: 25-35 MPG (6.7-9.4 L/100km)
  • Full-Size Sedan: 20-30 MPG (7.8-11.8 L/100km)
  • Hybrid: 40-60 MPG (3.9-5.9 L/100km)

SUVs and Trucks

  • Compact SUV: 25-30 MPG (7.8-9.4 L/100km)
  • Midsize SUV: 20-25 MPG (9.4-11.8 L/100km)
  • Full-Size SUV: 15-20 MPG (11.8-15.7 L/100km)
  • Pickup Truck: 15-25 MPG (9.4-15.7 L/100km)

Calculating Fuel Costs

Using MPG

  1. Distance ÷ MPG = Gallons needed
  2. Gallons needed × Price per gallon = Total cost

Example (MPG)

300-mile trip, 30 MPG, $3.50/gallon:

  • 300 ÷ 30 = 10 gallons
  • 10 × $3.50 = $35.00

Using L/100km

  1. (Distance ÷ 100) × L/100km = Liters needed
  2. Liters needed × Price per liter = Total cost

Example (L/100km)

500 km trip, 7 L/100km, €1.50/liter:

  • (500 ÷ 100) × 7 = 35 liters
  • 35 × €1.50 = €52.50

Factors Affecting Fuel Efficiency

Driving Habits

  • Aggressive driving: Reduces efficiency by 15-30%
  • Speeding: Every 5 mph over 50 reduces efficiency
  • Idling: Wastes 0.2-0.5 gallons per hour
  • Smooth acceleration: Improves efficiency

Vehicle Maintenance

  • Tire pressure: Under-inflation reduces MPG by 0.2% per PSI
  • Engine tune-up: Can improve efficiency by 4%
  • Air filter: Clean filter improves by up to 10%
  • Motor oil: Using recommended grade improves 1-2%

External Factors

  • Weather: Cold weather reduces efficiency
  • Terrain: Hills and mountains decrease MPG
  • Load: Extra 100 lbs reduces MPG by 1%
  • Aerodynamics: Roof racks reduce efficiency by 2-8%

Tips to Improve Fuel Efficiency

Driving Techniques

  1. Maintain steady speed: Use cruise control on highways
  2. Anticipate stops: Coast to red lights
  3. Avoid excessive idling: Turn off engine if waiting > 30 seconds
  4. Combine trips: Plan errands efficiently
  5. Remove excess weight: Clean out trunk and cargo areas

Vehicle Maintenance

  1. Check tire pressure monthly
  2. Regular oil changes
  3. Replace air filters as needed
  4. Keep engine tuned
  5. Use recommended motor oil

Comparing Vehicles

When Shopping for a Car

  • Compare EPA ratings (US) or WLTP ratings (Europe)
  • Consider both city and highway efficiency
  • Calculate annual fuel costs based on your driving
  • Factor in fuel type (regular vs. premium)

Real-World vs. Rated MPG

Actual fuel economy is typically 10-20% lower than EPA ratings due to:

  • Real-world driving conditions
  • Traffic and stop-and-go driving
  • Climate control usage
  • Individual driving habits

Electric Vehicles (EVs)

EVs use MPGe (miles per gallon equivalent) or kWh/100km:

  • MPGe: Compares energy content to gasoline
  • kWh/100km: Kilowatt-hours per 100 kilometers
  • Typical EV: 100-130 MPGe or 15-20 kWh/100km

Conclusion

Understanding fuel efficiency conversions between MPG and L/100km helps you compare vehicles internationally, calculate fuel costs, and make informed decisions about your transportation. Remember that lower L/100km and higher MPG both indicate better fuel efficiency.

For quick fuel efficiency conversions, use our Fuel Consumption Converter tool!