In-depth

WLTP Explained: Simplifying Range and Efficiency

The WLTP is a global vehicle testing system that predicts fuel economy, emissions, and electric vehicle range.

June 5, 2024       14 min read
wltp pic

What is WLTP Range?

WLTP range is the maximum distance an EV will travel on a single charge, based on a standardised test.

The range is calculated by running the test cycle (WLTC) twice and measuring energy consumption from the battery’s available capacity.

Range = usable battery energy ÷ energy consumption from the battery

Take the 2022 Jaguar I-Pace 🚙, for example:

470 km (range) = 84,700 Wh (usable battery) ÷ 180 Wh/km (energy consumption from the battery).

The range is published by Jaguar, as well as the usable battery. From those two numbers, we can estimate the battery consumption (something that WLTP uses only in calculations but is typically not published).

WLTP City Range

A few manufacturers list “City Range.” The city calculation is from the WLTP test cycle, where only the Low and Medium phases are used.

The city range applies to very few situations. You would have to be driving under 60 km/h all the time.

WLTP Combined Range

WLTP combined range is the range calculated from the low-speed (city) AND high-speed (highway) test phases.

This is a complete calculation using the 4-phase test cycle rather than just the low and medium cycles.

Where a manufacturer lists “WLTP range”, – they mean WLTP combined range.

What is the WLTP cycle?

The WLTP test cycle (WLTC) consists of a series of starts, accelerations, and stops in a controlled environment over a set period of time.

The test is carried out at an ambient temperature of 23°.

The 30-minute cycle is split into 4 phases, named after their respective maximum speeds:

Max Speed (km/h)Average Speed (km/h)Duration
Low56.525.79:49
Medium76.644.57:13
High97.460.87:35
Extra High131.3945:23

The average speed of the cycle is 46.5 km/h.

WLTP Test Cycle

WLTP Efficiency or Driving Economy?

The WLTP measures electric energy consumption. This is called efficiency or rated consumption.

However, you can also see efficiency readings on your vehicle’s dashboard.

What you see on your vehicle’s dashboard is not WLTP consumption.

  1. WLTP consumption is expressed as Wh/km and is based on “recharged electric energy from the mains.”
  2. Dashboard or driving efficiency is expressed as kWh/100 km or km/kWh and is measured by the vehicle from electric energy stored in the battery.

Many websites and online publications mix the two up.

How do they mix it up?

You’ll often read reviews: “This EV has a WLTP efficiency of 15.6 kWh/km, but I was able to get 14.5 kWh/100km”.

Unless the reviewer had a sophisticated setup that accurately recorded charging power and applied that to the dashboard consumption – they’ve compared an apple with an orange.

WLTP-rated consumption includes charging loss

  • WLTP performs a battery recharge as part of its test, so consumption includes charging losses.
  • WLTP efficiency allows consumers to compare energy costs (just like litres per 100 km in a petrol car).
  • Electricity ‘lost’ during charging is typically between 7-12% (worse in cold weather).

Dashboard efficiency does not include charging loss

  • The consumption you see on your dashboard does NOT include charging losses.
  • It measures the vehicle’s efficiency (weight, powertrain, aerodynamics) and your driving conditions.
Hyundai IONIQ 5 dashboard consumption

Driving consumption can be estimated by dividing the usable battery capacity by the WLTP range.

Battery capacity: usable, net, or total?

A battery’s usable (net) capacity is the amount of electricity the car can access.

The battery’s management system reserves some electrons to aid stability and sustainability.

This ‘restricted’ electricity is neither drained nor charged, so including it in an efficiency equation is incorrect.

Unfortunately, not all manufacturers publish usable battery amounts (so sometimes this spec is estimated).

See more about EV battery design.

Efficiency differences in EVs with similar Range and Battery

Consider three fictional EVs with matching gross battery capacity and range.

Fictional EVSparky McPlug-inShock-Mobile 250Electra GT
Battery60 kWh60 kWh60 kWh
Usable57 kWh57 kWh58 kWh
Range400 km400 km400 km
Charging loss10%12%10%

You might assume they would have the same efficiency.

  • The most efficient is the Sparky McPlug-in. It uses the least amount of mains electricity to travel its 400 km.
  • The Shock-mobile needs more electricity to fill its battery due to a higher charging loss.
  • The Electra GT is the least efficient. It has more usable capacity and, therefore, needs more recharging.

The only metric that can compare these is WLTP consumption.

What is ‘real-world’ range?

The so-called ‘real-world’ range is not an official measure.

  • Our actual or real range will differ because none of us drives in WLTP test cycles.
  • Some of us do mostly highway driving, and some primarily do urban driving. Which is “real”?

The WLTP cycle is poor at estimating motorway driving and cold-weather driving.

It’s conducted at 23° – not something you’ll see in winter. Neither the heater nor the air conditioning system is used during a WLTP test.

Cold temperatures, fast speeds, and wind will all lower range (see more in the buyer’s guide).

Has anyone tested the real-world range?

Yes. In Norway, enthusiasts routinely test the range of many EVs.

These findings show:

In a Norwegian winter (0° to -10°), the vehicles have a 10-28% lower range than WLTP.

Helpful, but it is not comparable to an NZ winter. Remember that WLTP is undertaken at 23°, so the nearer your locality is to that temperature, the more accurate the WLTP range will be.

Can you rely on real-world range?

All references to real-world range are estimates. They are not based on a scientific test but can be helpful.

What are TEH and TEL (Vehicle H and Vehicle L)?

Sometimes referred to as Test Energy Low or Vehicle Low, this has nothing to do with the low or high phases in the test cycle.

High and Low tests refer to the vehicle configuration used in the WLTP test.

Different variants or trims may alter range and energy consumption within a vehicle model family. The WLTP takes that into account (in conjunction with the manufacturer).

A 40 kWh Nissan Leaf 🚙 has different trim levels with either 16″ or 17″ wheels (Japan and UK imports).

The smaller wheels mean more range (285 km) than the 17″ (270 km). The smaller wheel trim would be TEL (or Vehicle L), the larger wheel trim would be TEH (Vehicle H).

Many things can affect range: tyre rolling resistance, changes to body trim might affect aerodynamics, and other add-ons might add weight.

  • Vehicle H (energy high) refers to the model trim with the highest energy demand,
  • Vehicle L (energy low) is the model trim with the lowest energy demand.

Which range is the manufacturer listing? They should list the range and consumption figures matching the vehicle trim being sold.

Have all vehicles been through the WLTP cycle?

No. WLTP only became law in Europe in 2017, using the NEDC cycle before that. In this situation, the WLTP range is estimated.

The USA uses a different test (EPA), while China uses its test cycle (CLTC).

CLTC vs. WLTP

The China Light-Duty Vehicle Test Cycle (CLTC) is considerably more optimistic than the WLTP.

Designed for Chinese conditions and driving habits, it has only 3 phases (and lacks the extra high phase that the WLTP has).

CLTC to WLTP Conversion Factor: 0.82

Example: 500 km (CLTC) × 0.82 = 410 km (WLTP)

Conversion formulas are a blunt tool but helpful. Consider the range specs of the following Chinese-manufactured vehicles:

Actual dataNEDCCLTCWLTP
BYD Atto 3480 km510 km420 km
BYD Dolphin420 km340 km

EPA vs. WLTP

The US Environmental Protection Agency (EPA) test combines a highway test (short, high-speed test – the HWFET) with an urban driving cycle (UDDS). The result is then multiplied by 0.7 to get a more realistic figure.

Actual dataEPAWLTP
Hyundai Kona (2020)258 miles484 km
Nissan Leaf 40 kWh (2020)150 miles270 km
Volkswagen ID.4 Pro (2023)275 miles519 km

EPA (miles) to WLTP (kilometres) Conversion Factor: 1.88

This converts to kms, and applies an EPA to WLTP conversion factor of 1.16

Example: 275 miles (EPA) × 1.88 = 517 km (WLTP)

NEDC vs. WLTP

The New European Driving Cycle (NEDC), is not new anymore. Developed in the 1970s, it has been superseded by the WLTP.

The NEDC has a simple 20-minute test cycle, most of which is at 50 km/h or under. For EV range, NEDC is far more generous than WLTP.

NEDC to WLTP conversion factor: 0.85

Example: 535 km (NEDC) × 0.85 = 444 km (WLTP)

What is 3P-WLTP?

3P-WLTP means three-phase WLTP, using only data from the first three phases of the test cycle.

However, this only applies to emissions data, and all fully electric vehicles are assigned a value of zero emissions. WLTP range is listed (by both the manufacturer and on the vehicle label) using 4P-WLTP (i.e. the complete cycle).

WLTP Test Cycle Outline

The complete test for an electric vehicle consists of the following phases:

  1. Start at full battery.
  2. Dynamic Segment 1: Drive the 4-phase cycle, followed by a 2-phase low-medium cycle (city).
  3. Drive at 100 km/h for a period of time.
  4. Dynamic Segment 2: Drive the 4-phase cycle, followed by a 2-phase low-medium cycle (city).
  5. Drive at 100 km/h until battery depletion.
  6. Recharge the battery to 100%.

During the test, the electrical current and voltage pulled from the battery are measured (p. 744).

The WLTP mentions, “the manufacturer may use the on-board current measurement data. The accuracy of these data shall be demonstrated to the approval authority.

These measurements are kept from the start of the test until the end (break-off).

During the recharge, measuring equipment is placed between the charger and the mains to measure recharged electric energy.

How is electric range calculated? (p. 767)

Electric range (km) = usable battery energy (determined by measuring consumption until break-off (Wh) / electric energy consumption (Wh / km).

Electric energy consumption (EC) is calculated by:

EC (Wh/km) = electric energy change during cycle period (Wh) / distance travelled (km).

Where energy change = (voltage x current over time) / 3600 (to give Wh).

How is WLTP efficiency calculated? (p. 764)

The WLTP refers to this as electric energy consumption, but with a different definition: “Electric energy consumption of the applicable WLTP test cycle based on the recharged electric energy from the mains and the pure electric range”.

It’s very confusing that “energy consumption” refers to recharged energy or energy directly from the battery.

Efficiency (Wh/km) = Recharged electric energy from the mains (Wh) / Electric range (km).

Complete example

Sparky McPlugin is placed on the dynamometer with a full charge. The driver follows the test cycle and determines the EV uses 6,090 Wh over 42 kilometres. So the battery consumption is 145 Wh / km.

The battery is depleted and then recharged back to 100%. The total energy depleted from the battery is 57,000 Wh. The total energy used to recharge is 63,450 Wh (about 6,000 Wh of charging loss).

Electric range is 57,000 Wh / 145 Wh per km = 393 km.

WLTP efficiency (rated consumption) is 63,450 Wh / 393 km = 161 Wh / km.

Why the two ‘dynamic segments’?

You’ll notice no regeneration if you’ve ever driven your EV at 100% battery charge. You are also going from a cold start (also more consumption).

The phase repetitions account for this difference. More energy is used in the first instance. These two cycles are averaged to provide a single consumption figure.

This is also weighted against the total battery size (the first segment is weighted against the total capacity). Therefore, a large battery will have less of the first segment in the final WLTP rating.

Sounds tricky? It’s pretty clever.

What are the 100 km/h sections for?

They are there to shorten the test and deplete the battery. The battery is drained so it can be recharged (therefore providing the efficiency rating of the vehicle).

Why is there a 4-phase AND a 2-phase?

The data captured in the 2-phase is used for the CITY range and is not ‘added’ or included in the combined calculator.

References

  • The complete WLTP standard (all 839 pages of it). A great read if you have trouble sleeping.
  • “A test vehicle (vehicle H) with the combination of road load relevant characteristics (i.e. mass, aerodynamic drag and tyre rolling resistance) producing the highest cycle energy demand shall be selected from the family” p. 571
  • WLTP: Worldwide Harmonised Light Vehicle Test Procedure
  • Vehicle classes – almost all EVs in NZ fall into the Class 3b category (i.e., they can go faster than 120 km/h).
  • Electrive
  • Dieselnet
  • NZ conversion factor consulting report (PDF).

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