A new method of certification of vehicles WLTР – what does it mean

From September 2018 in Europe became mandatory new rules of certification of vehicles based on a new procedure for measuring fuel consumption and emissions of toxic components. These routines are now calculated using the test methods WLTP, which has replaced the old methodology – NEDC.

The name of the WLTP stands for Worldwide Harmonized Light Vehicles Test Procedure, and the translated – Harmonized test procedure for passenger vehicles.

The introduction of the methodology WLTP two main goals:

  • to replace aging pipes and loops of the ride and the method of measurement, because under the old rules the car legally had the real fuel consumption is higher (sometimes by as much as 42%) than the “official” specified by the manufacturer;
  • to do this technique the same for all countries (i.e., harmonize). Because until then, in Europe the cars were tested on the NEDC cycle, in America by three methods FTP-75, US06, and HWFET, in Japan JC08 used in China – something else.


What’s wrong with the old methodology of NEDC

Certification tests by the methodology of NEDC was conducted on a specially prepared for this purpose copies of cars. Automakers were given for testing is not standard curb production cars, and lightweight, with a minimum of equipment, narrow tires, and even with a more liquid oil.

In addition, the driving modes used in the test NEDC, outdated, and compatible with about 70-ies of the last century. Thus, according to the NEDC, it was believed that the car in the middle needs to be accelerated to 50 km/h in 26 seconds in the “city” and up to 70 km/h in 41 seconds on the track. Naturally, with all these conditions, test vehicle and fuel consumption, and emissions were much less than that of conventional cars on the road.


 How does the test WLTP

WLTP test itself lasts 30 minutes. At this time, the test bench simulates three driving modes – urban, country road and autobahn. The car accelerates to 60, 80, 100 and 130 km/h Acceleration, accelerate, slow down, and all the time off the fuel consumption and the emission of substances into the atmosphere.

Depending on the vehicle class (determined by the ratio of the rated power of the engine to the mass of vehicle in running order – P/Wr), used three types of tests WLTP.

Classes of cars:

  • Class 1 – cars with a PWr <= 22 W/kg;
  • Class 2 – vehicles with 22 <PWr <= 34;
  • Class 3 – vehicles that have the PWr> 34.

Currently, the majority of cars belongs to class 3.

What is different from the NEDC WLTP test

The main difference: on the test bench is not specially modified for the test machine (the so-called “perfect car”), and the samples for each combination of engine-transmission from a number of vehicles. Moreover, with the wide tires, maximum vehicle additional equipment, and with the most “unfavorable aerodynamics”.

The terms of the WLTP tests as close as possible to the present day, that is, used a more dynamic test cycle – fewer stops and idling, performance accelerations correspond to today’s realities.

Certification rules for WLTP recommend that manufacturers indicate in the technical documentation of the highest rates of tests for fuel consumption and emissions of harmful substances.


The main differences between the NEDC and WLTP test (vehicle class 3)

Test conditionsWLTPNEDC
Test time30 minutes (1800 s)20 minutes
The room temperature23°C20°C – 30°C
Mileage in the same driving mode23.3 km11 km
Maximum test speed131 km/h120 km/h
Average speed without stopsOf 46.6 km/h for34 km/h
The proportion of stops13.4% of24,8%
Maximum accelerationOf 1.58 m/S2 
The use of additional equipment (climate control, heated seats)YesNo
The regime “movement on the rise”MissingMissing


As a test WLTP is applied to electric and plug-in hybrids

Electric cars tested before NEDC also got unrealistic results. It is assumed that now check on WLTP, they will show their true potential.

But there is one “but”. The WLTP tests are conducted at 23°C is the optimum temperature for battery cars. Meanwhile, you know – electric cars in the cold significantly decreases the reserve. So there are questions…

Significant changes were made and testing plug-in hybrids. These machines are tested several times. At the first stage of the plug-in hybrid should be a fully charged battery. The test cycle is repeated until then, until the battery is “sit”. Followed by a test phase with a low battery. At this time works only internal combustion engines and battery supplied energy recovery. From the results of these two stages are calculated averages.

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WLTP is used not only for releasing the first models of cars

The WLTP testing is mandatory for every new vehicle offered for sale. This applies not only to models of the newcomers, but also those that were developed several years ago, but they still continue to produce.

As certification WLTP – an expensive process, automakers began to shoot production versions, sales are low.

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Test stands is not enough

This is because each automaker many types of cars it manufactures. And test stands that have passed the verification and licensing, a limited number.

For example, only one VW now off the Assembly line 260 combinations of engine-transmission. Therefore, to date, the testing of its products takes place at the 21st booth in three shifts. And the output of those models that have not been certified by WLTP, is temporarily suspended.


Which countries already apply the WLTP

Today it is the 28 EU countries and Norway, Iceland, Switzerland, Liechtenstein, Turkey and Israel. Later this year it will introduce in India, Japan and South Korea. China and the United States have not yet decided.

On the way the test is even tougher – RDE

I think WLTP – hard? No, it’s flowers. From 1 September 2019 to him for help will drive the RDE test, we are deciphering how the Real Driving Emissions – emissions in real conditions. In this test a special device, which measures emissions of nitrogen oxide and soot will be attached to the car. And the testing will take place in real city traffic, country road and motorway.

Control will only be for the first time released a new model, and the tightening of standards, RDE will take place in two stages. On the ground in real conditions will permit the excess “laboratory” limit on the emission of harmful substances in 2.1 times. That is, a limit on nitrogen oxide for diesel cars in the 80 mg/km will be allowed to exceed on the road to 168 mg/km In the second phase, from 2020, the ratio of the tolerance will be reduced to 1.5.

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