WLTP Range and Efficiency: Complete Guide
WLTP is a global vehicle testing system that predicts fuel economy, emissions, and electric vehicle range.
New Zealand uses this standard for vehicle emissions and range estimates.
What is the WLTP Cycle?
The WLTP cycle 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 (WLTC) is split into 4 phases, named after their respective maximum speeds:
|Max Speed (km/h)||Average Speed (km/h)||Duration|
Test Cycle Graph
The average speed of the cycle is 46.5 km/h.
What is WLTP Range?
WLTP range is calculated by running the test cycle twice and measuring energy consumption from what is available in the battery.
Range (km) = usable battery energy (Wh) / energy consumption from battery (Wh/km)
Take the 2022 Jaguar I-Pace 🚙, for example:
470 km (range) = 84,700 Wh (usable battery) / 180 Wh/km (energy consumption from 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 is not appropriate for the New Zealand environment. You would have to be driving ONLY in 60 km/h zones all the time.
WLTP Combined Range
Most manufacturers list the combined range. This is a complete calculation using the 4-phase test cycle, rather than just the low and medium.
Where a manufacturer lists “WLTP range,” – they mean WLTP combined range.
WLTP Efficiency or Driving Economy?
Sometimes referred to as efficiency, the WLTP measures electric energy consumption.
It’s important to understand there are effectively two different measures.
What you see on your vehicle’s dashboard is not WLTP efficiency.
- WLTP efficiency is expressed as Wh/km and is based on “recharged electric energy from the mains“.
- 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 156 Wh/km but I was able to get 14.5 kWh/100km”.
Unless the reviewer had a very sophisticated setup that accurately recorded charging power, and applied that to the dashboard consumption – they’ve compared an apple with an orange.
WLTP-rated efficiency 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).
- Note that 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’s a combination of the vehicle’s efficiency (weight, powertrain, aerodynamics), and your driving conditions.
Driving consumption can be estimated by dividing the usable battery capacity by the WLTP range.
Battery capacity: usable, net, or total?
The usable (net) capacity of a battery is the amount of electricity that the car can access.
The battery’s management system reserves a certain amount of electrons in the battery to help stability and sustainability.
This ‘restricted’ electricity is neither drained nor charged. Therefore including at as part of an efficiency equation is incorrect.
Not all manufacturers publish usable battery amounts. Some publish the usable and not the gross.
|Fictitious EV 1||Fictitious EV 2|
|Battery||60 kWh||60 kWh|
|Usable||57 kWh||58 kWh|
|Range||400 km||400 km|
Both EV1 and EV2 have the same battery and range.
You might assume they would have the same efficiency.
However, EV2 has more usable and suffers greater charging loss, therefore, uses more electricity, making it less efficient than EV1.
See more about EV battery design.
What is real range?
The so-called “real” range is not an official measure.
- Because none of us drive in WLTP test cycles, our actual or ‘real’ range will differ.
- Some of us do mostly highway driving, and some primarily do urban driving. Which is “real”?
- Real is not a great word to use.
The WLTP cycle is poor at estimating motorway driving.
It’s also conducted at 23° – not something you’ll see in an NZ 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).
On EVDB, both the official WLTP range and a highway range estimate are listed.
Has anyone tested the “real” range?
Yes. In Norway, a group of enthusiasts routinely test the range of many EVs.
These findings show:
In a Norwegian winter (0° to -10°), the vehicles have a 10-20% lower range than WLTP.
Helpful, but that 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” range?
All references to real 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.
Sometimes in a vehicle model family, you can have different variants or trims that will alter range and energy consumption – so WLTP takes that into account (in conjunction with the manufacturer).
The 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). It looks like NZ New Leafs only have the 17″, so Nissan NZ appears to list the Vehicle H WLTP range.
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.
So which range is the manufacturer listing? I’ve noticed it varies, and they should be listing Vehicle High.
Have all vehicles been through the WLTP cycle?
No. WLTP only came into law in Europe in 2017, using the NEDC cycle prior to that. In this situation, the WLTP range is estimated.
The USA uses a different test (EPA).
WLTP Test Cycle Outline
The complete test for an electric vehicle consists of the following phases:
- Start at full battery.
- Dynamic Segment 1: Drive the 4-phase cycle, followed by a 2-phase low-medium cycle (city).
- Drive at 100 km/h for a period of time.
- Dynamic Segment 2: Drive the 4-phase cycle, followed by a 2-phase low-medium cycle (city).
- Drive at 100 km/h until battery depletion.
- Recharge battery to 100% (measuring power consumption)
Why the two ‘dynamic segments’?
If you’ve ever driven your EV at 100% battery charge, you’ll notice there is no regeneration. You are also going from a cold start (also more consumption).
The repetitions of the phase account for this difference. More energy is used in the first instance. These two cycles are averaged to provide a single consumption figure.
Because we need more complexity, they are 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 really.
What are the 100 km/h sections for?
They are NOT used in the range calculation.
They are there to shorten the test and deplete the battery. The battery is drained so it can be recharged again (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.