WLTP, NEDC, Euro 6.1, Euro 6.2 & RDE

The old NEDC (New European Driving Cycle) is being replaced by the new WLTP (Worldwide Harmonized Light Vehicles Test Procedures) which is a longer cycle more representative of real world driving. The economy figures obtained from WLTP are more reflective of customers’ actual experience.

Additionally vehicles also need to prove their air quality credentials by passing the RDE (Real Driving Emissions) test. This is done by using sensitive analysis equipment to the trace tailpipe emissions of pollutants, including NOX and particulates, while the car is driven in a wide range of both every-day and extreme conditions.

We will be sharing new fuel consumption figures based on the new European fuel consumption test, the WLTP driving cycle (Worldwide Harmonized Light Vehicles Test Procedure), introduced in September 2017. By testing cars with extra optional equipment and across a greater range of driving profiles, we can give you fuel consumption figures that are a closer representation of real-world driving behaviour than the current fuel consumption test, the NEDC. The driving cycle of the WLTP ("Worldwide Harmonized Light Vehicle Test Procedure") addresses key criticisms of the NEDC ("New European Driving Cycle"). In particular, the new WLTP driving cycle driving profile corresponds more closely to nowadays everyday operation, and it is not just measured for a base vehicle, but also takes into account the influence of additional optional equipment.

The whole Vauxhall range now meets the new requirements with full availability of WLTP-certified cars.

What is NEDC?​

NEDC = New European Driving Cycle and was the official emissions test

This is a laboratory test in strict conditions monitored by a government-appointed independent approval agency (VCA). It was first introduced in 1992 and is based on a theoretical driving profile. It has two parts -the first simulates city traffic with many stop/start phases, and the second corresponds to an extra-urban journey at a maximum speed of almost 75 mph

It allows fuel consumption comparison of different vehicles. However it doesn’t reflect the fuel consumption of day-to-day driving, and hence real consumption can be very different.​


The NEDC (New European Driving Cycle) was introduced in 1992. But since then, cars, roads and driving behaviour have changed quite a bit. It’s is an artificial laboratory test and serves exclusively to compare different vehicles, not to reflect day-to-day driving and fuel consumption. This means that real consumption today is often very different from the NEDC information. The main reasons include:

  • The theoretical driving profiles it uses don’t match real user profiles. 
  • Insufficient acceleration. 
  • Too many stop phases. 
  • It doesn’t incorporate higher speeds. This sets the average speed too low. 
  • Gear shifting points are broadly defined by transmission type. So they are the same for all cars with manual transmission. 
  • Optional equipment is not being taken into account.


The NEDC is an artificial laboratory test that serves exclusively to compare the fuel consumption of different vehicles. But it doesn’t reflect the fuel consumption of day-to-day driving. This means that real consumption today is often very different from the NEDC information. The main reasons include:

  • The theoretical driving profiles it uses don’t match real user profiles. 
  • Insufficient acceleration. 
  • Too many stop phases. 
  • It doesn’t incorporate higher speeds. This sets the average speed too low. 
  • Gear shifting points are broadly defined by transmission type. So they are the same for all cars with manual transmission. 
  • Optional equipment is not being taken into account.


The NEDC is based on a theoretical driving profile and consists of two parts. In the first 13 minutes, it simulates a drive in city traffic with many stop-and-go phases. The second part corresponds to an extra-urban journey at a maximum speed of 120 km/h, almost 75 mph.

What is WLTP?

WLTP = Worldwide Harmonized Light Vehicles Test Procedures and is the new test cycle that replaces NEDC.

This is also laboratory test but is based on a global statistical survey of real driving profiles. It has four parts with different average speeds: low, medium, high and extra high. Each phase includes different amounts and degrees of acceleration, braking and stopping, all to simulate everyday driving.

WLTP results in higher CO2 and consumption figures but the values will be more realistic to real world experience. WLTP also takes into consideration option content and this generates dependent and unique CO2 and consumption figures.

Click here to see new WLTP Driving Cycle figures for Vauxhall Astra and Vauxhall Insignia

WLTP means that the economy figures become more reflective and consistent with driving experience, but the additional requirement of the real world evaluation (RDE) ensures a greater transparency.

This will result in official economy figures increasing as their parity to the real world becomes more consistent.

In order to determine consumption values more realistically, the WLTP driving cycle is based on a global statistical survey of real driving profiles. It includes four parts with different average speeds: low, medium, high and extra high. Each phase includes different amounts and degrees of acceleration, braking and stopping, all to simulate everyday driving.

NEDC and WLTP differences

Since the introduction of NEDC in 1992 cars and driving styles have changed quite a bit. The WLTP test parameters have been redefined to reflect real conditions more closely. They now include:

  • Longer cycle times (30 min vs 20 min)
  • Shorter stopping times (13% vs 25%)
  • Longer distances (about 23 km/14 miles vs 11 km/6 miles)
  • Higher speeds (max. 130 km/h / 80 mph vs 120 km/h / 75 mph)
  • Almost 50% higher average speeds
  • Higher maximum acceleration and more acceleration phases
  • Approximately 20-30% higher driving power based on the more dynamic driving situations
  • More realistic determination of driving resistance for fuel consumption tests
  • Consideration of optional equipment in the vehicle

The values obtained with WLTP are comparable worldwide, while the NEDC values are only valid in Europe.

Real Driving Emissions / Euro 6

Real Driving Emissions (RDE) works by fitting equipment called a Portable Emissions Measurement System (PEMS) to the vehicle, which measures emissions while the vehicle is driven on the road.

Given the huge differences in temperature, road and vehicle conditions as well as driving styles, no lab test can ever replicate exactly what happens on the road. RDE testing will demonstrate that new cars’ low emissions are achieved in these real world conditions.

RDE will also include some extreme driving conditions, rarely encountered by most motorists, for example carrying a heavy load up a steep hill at high speed in very low temperatures.

Under the new emission standards as of Euro 6d-TEMP, vehicles will have to prove their claimed emissions output in the future under more stringent test conditions. This means that the limit values for nitrogen oxides (NOx) and particle emissions not only have to be complied with under the new WLTP laboratory conditions, but they must also be verified in an everyday test.

Therefore, the RDE test procedure (Real Driving Emissions) does not require a fixed driving cycle; distance, acceleration, outside temperature, wind conditions and traffic conditions are freely selectable within given statistical boundary conditions.

Each engine/transmission combination of a certain vehicle type is tested with the most economical as well as the most fuel-intensive vehicle equipment. While the introduction of WLTP has resulted in an increase of published fuel consumption figures and CO2 values, these are now much closer to the actual fuel consumption and CO2 emissions.

Why are WLTP figures higher compared to NEDC?

Due to more realistic test conditions, the fuel consumption and CO2 emissions measured under WLTP are in many cases higher compared to those measured under NEDC. The daily fuel consumption of a vehicle depends very much on the individual usage profile and where and how it is being driven: city traffic, country roads or motorways. These differences are better accounted for by the WLTP driving cycle. Instead of calculating only the values "urban, extra-urban and combined", WLTP provides four individual values for different predetermined travel profiles (low, medium, high, and extra-high) that are based on statistical surveys and the analysis of user profiles and averages. In addition, the WLTP driving cycle is much more dynamic than the NEDC and reflects higher accelerations, a higher average speed and a higher maximum speed.

 Each engine/transmission combination of a certain vehicle type is tested with the most economical as well as the most fuel-intensive vehicle equipment. While the introduction of WLTP has resulted in an increase of published fuel consumption figures and CO2 values, these are now much closer to the actual fuel consumption and CO2 emissions.

NEDC and BIK Backdating

​Until 6th April 2020 (SMMT Proposal), VED/BIK will continue to be determined using a NEDC-type value. Since the NEDC cycle has been replaced, this figure will be “back-correlated”or calculated from approved WLTP datausing COMPAS (an EU Commission Tool supported by ACEA).

The back-correlated NEDC CO2 does not take into consideration option content, and therefore options (except tyres) will not effect VED/BIK until 6th April 2020.

Additionally the CAFE (Corporate Average Fuel Economy) 2020 target will not change, and will continue to be monitored using “back-correlated” NEDC.

When does WLTP come in to force?

1st September 2017

  • Euro 6d TEMP (Euro6.2) is required for all new types of cars (Cat-M1)


1st September 2018

  • Euro 6d TEMP (Euro6.2) is required for all new registrations of cars. End-of-series derogation is approved but is more restricted than previously.


1st January 2019 [SMMT proposed date]

  • WLTP economy data used in all communication including advertising


6th April 2020 [SMMT proposed date]

  • HMRC start using WLTP economy data for VED and BIK.


SMMTproposed dates took into consideration industry consultation to which Vauxhall contributed. Dates are currently with Ministry for approval.