Liters per 100 Kilometers (L/100km) - Unit Information & Conversion

Quick Answer: What is L/100km?

Liters per 100 kilometers (L/100km) is the metric standard for fuel consumption. It answers the question: "If I drive 100 kilometers, how many liters of fuel will I use?"

• LOWER is Better:
  • 5 L/100km = Very Efficient (Hybrid/Diesel)
  • 8 L/100km = Average (Sedan)
  • 12+ L/100km = Inefficient (SUV/Truck)
• The "Consumption" Mindset: It measures cost directly. If fuel is €2/liter, a 10 L/100km car costs exactly €20 to drive 100 km.
• Key Conversions:
  • 5 L/100km ≈ 47 MPG (US)
  • 10 L/100km ≈ 23.5 MPG (US)

It is the official standard in Europe, Canada, Australia, and New Zealand.

L/100km Comparison Table

L/100km	Efficiency Rating	MPG (US)	MPG (UK)	km/L
3.0	Hyper-efficient	78.4	94.2	33.3
4.0	PHEV / Hybrid	58.8	70.6	25.0
5.0	Excellent	47.0	56.5	20.0
6.0	Very Good	39.2	47.1	16.7
7.0	Good	33.6	40.4	14.3
8.0	Average	29.4	35.3	12.5
10.0	Below Avg	23.5	28.2	10.0
12.0	Poor	19.6	23.5	8.3
15.0	Very Poor	15.7	18.8	6.7
20.0	Truck/Supercar	11.8	14.1	5.0

Definition

Liters per 100 Kilometers (symbol: L/100km or l/100km) is a unit of fuel consumption.

Formula: $$ \text{Consumption (L/100km)} = \left( \frac{\text{Fuel Used (Liters)}}{\text{Distance (Kilometers)}} \right) \times 100 $$

Why "Consumption" vs. "Economy"?

• Economy (MPG, km/L): Focuses on distance. "How far can I go?"
• Consumption (L/100km): Focuses on fuel. "How much will it cost?" From an engineering and environmental standpoint, consumption is more useful because it scales linearly with cost and pollution.
• Saving 1 L/100km always saves the same amount of fuel over a given distance.
• Increasing MPG by 1 does not always save the same amount (the "MPG Illusion").

History

The European Standard

As the automotive industry developed in Europe (Germany, France, Italy), engineers needed a way to quantify engine efficiency. Since the metric system was already established, measuring the volume of fuel (liters) over a standard distance (100 km) became the norm.

Canadian Metrication (1970s)

Canada provides a unique case study.

• Pre-1975: Used Imperial MPG (UK gallons).
• Post-1975: Switched to L/100km.
• Today: While the official sticker is L/100km, many Canadians still mentally convert to MPG, leading to a confusing mix of US MPG, UK MPG, and L/100km in daily conversation.

The WLTP Era (2017-Present)

The Worldwide Harmonised Light Vehicle Test Procedure (WLTP) is the modern global standard for testing cars. It reports results primarily in L/100km (and CO2 g/km) because these metrics are essential for calculating carbon taxes and fleet emission targets in the EU.

Real-World Examples

Vehicle Benchmarks (2024)

What do the numbers on the window sticker mean?

• 3 - 4 L/100km: Plug-in Hybrids (when charged) or small scooters.
• 4 - 5 L/100km: Toyota Prius, Hyundai Ioniq (Hybrids).
• 5 - 6 L/100km: Efficient diesel hatchbacks (VW Golf TDI) or small petrol city cars.
• 6 - 8 L/100km: The "Average" zone. Most compact SUVs (CR-V, RAV4) and sedans.
• 8 - 10 L/100km: Larger SUVs, minivans, and older sedans.
• 12 - 15 L/100km: Pickup trucks (F-150), large luxury SUVs, sports cars.
• 20+ L/100km: Towing heavy loads, driving a supercar at speed, or a tank.

The Cost of 100 km

If fuel costs €1.80 per liter:

• Car A (5 L/100km): Uses 5L. Cost = €9.00.
• Car B (10 L/100km): Uses 10L. Cost = €18.00.
• Car C (15 L/100km): Uses 15L. Cost = €27.00.
• The math is incredibly simple compared to MPG.

Common Uses

Where is it used?

• Europe: Exclusive standard.
• Canada: Official standard.
• Australia/NZ: Official standard.
• China: Official standard.
• South Africa: Official standard.

Emissions Regulations

Governments love L/100km because it links directly to CO2.

• Burning 1 Liter of petrol produces ~2.3 kg of CO2.
• Therefore, a 5 L/100km car emits 115 g CO2/km.
• A 10 L/100km car emits 230 g CO2/km.
• This linear relationship makes taxing pollution easy.

Conversion Mistakes to Avoid

1. The "Higher is Better" Habit

Mistake: A US driver sees "4.5 L/100km" and thinks it's terrible (because 4.5 MPG is terrible). Reality: 4.5 L/100km is amazing (52 MPG).

• Remember: Low Score Wins (like Golf).

2. The MPG Illusion (Linearity)

Mistake: Thinking that improving from 10 to 15 MPG is less important than 30 to 35 MPG. Reality: L/100km reveals the truth.

• 10 to 15 MPG = 23.5 to 15.7 L/100km (7.8L saved).
• 30 to 35 MPG = 7.8 to 6.7 L/100km (1.1L saved).
• Conclusion: Improving gas guzzlers saves massive amounts of fuel. L/100km makes this obvious.

3. US vs UK MPG Conversion

Mistake: Converting L/100km to "MPG" without specifying the gallon. Reality:

• 8 L/100km = 29.4 MPG (US)
• 8 L/100km = 35.3 MPG (UK)
• Always specify the country.

Detailed Conversion Charts

L/100km to MPG (US)

L/100km	MPG (US)	Note
2.0	117.6	Scooter
3.0	78.4	XL1 Concept
4.0	58.8	Prius
5.0	47.0	Hybrid
6.0	39.2	Civic
7.0	33.6	Camry
8.0	29.4	CR-V
9.0	26.1	Minivan
10.0	23.5	F-150 (V6)
12.0	19.6	V8 Truck
15.0	15.7	Towing
20.0	11.8	Heavy Load
30.0	7.8	Semi Truck

Physics of Fuel Consumption

Why 100 km?

100 km is an arbitrary but convenient distance (62 miles). It's long enough to average out minor fluctuations but short enough to be a relatable trip distance (e.g., driving to the next city).

Factors Increasing L/100km

1. Cold Starts: An engine uses 20-30% more fuel (higher L/100km) when cold. Short trips (< 5 km) result in terrible efficiency numbers.
2. Speed: Above 100 km/h, aerodynamic drag kills efficiency.
   • 90 km/h: ~6 L/100km
   • 120 km/h: ~8 L/100km (+33% consumption!)
3. Aggressive Driving: "Jackrabbit" starts dump fuel into the engine. Smooth driving lowers the number.

How to Lower Your L/100km

The "Eco-Driving" Style

1. Look Ahead: If the light is red 200m away, lift off the gas NOW. Coasting uses 0 L/100km.
2. Shift Up Early: If driving a manual, shift to a higher gear sooner. Lower RPMs usually mean lower consumption.
3. Cruise Control: On flat highways, computers are better at maintaining steady throttle than humans.

Vehicle Care

1. Tire Pressure: Low tires = dragging an anchor.
2. Aerodynamics: Close windows at highway speeds. Remove roof boxes.
3. Weight: Don't use your trunk as a storage locker.

Unit Frequently Asked Questions

What is a "good" L/100km?

• < 5: Excellent (Hybrid/EV territory).
• 5 - 7: Good (Modern compact car).
• 7 - 9: Average (Family SUV).
• > 10: Poor (Truck/Performance car).

How do I calculate L/100km manually?

1. Fill tank, reset trip to 0.
2. Drive 400 km.
3. Fill tank again. It takes 32 Liters.
4. Calculation: $(32 \div 400) \times 100 = 8.0$ L/100km.

Why does my trip computer fluctuate so much?

Instantaneous L/100km can show 0.0 (coasting) or 50.0 (accelerating hard). Look at the "Average" L/100km for a true picture.

How do I convert L/100km to MPG in my head?

Rule of Thumb: Divide 240 by the L/100km number.

• 8 L/100km -> 240 / 8 = 30 MPG. (Actual: 29.4).
• 6 L/100km -> 240 / 6 = 40 MPG. (Actual: 39.2).
• It's surprisingly accurate!

Is L/100km used for Electric Vehicles?

Sort of. EVs use kWh/100km (Kilowatt-hours per 100 km).

• Typical EV: 15 - 20 kWh/100km.
• Some people convert this to "Le/100km" (Liters equivalent) to compare with gas cars.

What is the L/100km of a Formula 1 car?

F1 cars are incredibly efficient engines but driven at maximum attack. They consume about 45 - 50 L/100km (roughly 5 MPG).

Quick Reference Card

Measurement	Value
Formula	(Liters ÷ km) × 100
5 L/100km	~47 MPG (US)
8 L/100km	~29 MPG (US)
10 L/100km	~23.5 MPG (US)
Hybrid Target	< 5.0 L/100km
Average Car	~7.5 L/100km
Mental Math	240 ÷ L/100km ≈ MPG

Your Next Steps

Master other fuel efficiency conversions:

• Kilometers per Liter - The inverse metric unit
• Miles per Gallon (US) - The US standard
• Miles per Gallon (UK) - The British standard
• Liter - The volume unit
• Kilometer - The distance unit