WLTP & Fuel Economy

Helping Drivers Choose the Best Car for Their Journeys.

The Worldwide Harmonised Light Vehicle Test Procedure (WLTP) is a new global regulation for measuring the level of air pollutants, CO2 emissions and energy consumption in light duty vehicles. It replaces the outdated New European Driving Cycle (NEDC) test that has been used for over 20 years. WLTP embraces an improved range of dynamic and robust testing procedures, and better reflects real-world driving conditions for all vehicle powertrains. These improvements produce much more accurate and realistic results, giving the consumer more confidence in fuel economy, CO2 emissions and electric range values presented for a new car. WLTP became mandatory for all new cars from September 2018.

Zemo Partnership Guidance Notes

Zemo Partnership is working with its stakeholder community to ensure the introduction of new WLTP data is of most benefit to the UK passenger car market and consumers.

We have published several guidance notes to assist the automotive industry to keep up to speed with policy changes and outline recommendations for presenting WLTP data in consumer information.

Consumer Information Guide

  • Providing recommendations for manufacturers presenting WLTP and NEDC equivalent figures in promotional material include car labels, websites and marketing and advertisements.


Automotive Industry Guide

  • Generic information for the automotive industry about the transition of WLTP into UK policy and recommendations for presenting new data in car buyer information.


Zemo Partnership Guides for Drivers

  • Many drivers are unsure about their next car choice and unaware of how the new WLTP figures can help. Our ‘Know Your Fuel Costs’ and ‘Know Your Electric Range’ guides are designed to overcome this, helping drivers make a more informed decision based around their own personal journeys. These are available in car dealerships as physical flyers, and can also be viewed on the right of this page.

Frequently Asked Questions

Why do we need a new fuel economy test?

Predicting how much fuel we might use in a new car is vitally important for drivers but can be very challenging. The current ‘official’ figures are primarily intended as a way of comparing different cars, but the test (known as the NEDC) has its origins in the 1970s and has not kept up with rapidly developing car technology, and has become less representative of ‘real driving’. This has led to a significant difference between the miles per gallon reported in the official test and what most drivers really achieve in normal driving. During normal driving conditions the fuel consumption can vary widely due to factors such as driving style, road and traffic conditions, vehicle options and weather etc.

With the increasing range of powertrain technologies available in today’s cars, it is important that car buyers have accurate and more realistic information about the performance and capability of new cars and can make a really informed decision about which will be best for their individual journey. To give a better picture of what fuel economy we might expect when choosing a new car, the automotive industry and governments have come together to develop a new CO2 and fuel consumption test which will give more realistic and representative figures. This test will also be used to measure the emissions which affect air quality.

Every new type of car model will be tested against WLTP starting from 1st September 2017, and as of September 2018 all new cars on sale will have WLTP test information available.

Importantly, the new WLTP test will become the only truly comparable measure across every car and manufacturer which is verified by governments and certification bodies and this data should not be confused or compared with other road tests or ‘real world’ indices.

How have test conditions been improved under WLTP?

WLTP tests are conducted in a laboratory to ensure accuracy and repeatability, but introduce much more representative testing conditions based on data from ‘real driving’ and will provide a more accurate basis for measuring emissions and calculating a car’s fuel consumption. This will provide consumers with more detailed and realistic car performance data. The new test involves a significant number of key changes compared to the ‘old’ NEDC test.

Realistic and broader range of driver journeys - from congested city driving to free-flowing motorway traffic:

  • Cycles based on real driving.
  • Fewer stops and less idling time.
  • Higher average and maximum speeds - including real motorway speeds.
  • Longer overall testing time - increased from 20 to 30 minutes

More realistic driving styles:

  • More dynamic acceleration and deceleration - typical of today's road traffic.
  • Representative gear changing points determined for each vehicle

More realistic test conditions:

  • Ambient temperature based on 14°C rather than between 20°C and 30°C.
  • Inclusion of optional equipment - fuel consumption figures are provided for specific vehicles as sold to the customer, with the options fitted.
  • Much better test preparation, set up and control - to reflect the capability of today’s facilities.

Why will WLTP type approved cars still have NEDC fuel consumption and CO2 figures?

Cars tested under WLTP will also have NEDC equivalent CO2 and fuel consumption values until 2020. Manufacturers must also continue to use the NEDC equivalent CO2 figure when reporting their fleet average CO2 emission performance of new cars (which were set against NEDC until 2020/2021).

In order to help car buyers compare fuel consumption and vehicle tax between different cars, some of which will be tested under the old NEDC test and some under the new WLTP test, the use of these "NEDC equivalent values will ensure appropriate comparisons are still possible during the transition. However, it is vital that NEDC and WLTP are not confused. A person could mistakenly think a car tested under WLTP was less efficient and so more expensive to run than a similar car tested under NEDC, which may show lower CO2 emissions, and better fuel economy. Avoiding this confusion is the primary aim of the working group.

Consumers are required to have access to new car CO2 and fuel consumption information at the ‘point of sale; under the Passenger Car (Fuel Economy and CO2 Emission Information) Regulations. This covers car labels, posters and displays at dealer/retailer showrooms and manufacturers; printed marketing materials including adverts and brochures.

The regulations were amended during the first week of June 2018 to take into account the introduction of WLTP. NEDC fuel consumption and electric figures will be used in consumer information until January 2019, then switch to WLTP.

The NEDC CO2 figure will continue to be shown until end of March 2020, then switch to the WLTP value.

What happens with vehicle tax?

Cars approved under WLTP will continue to be taxed against the NEDC CO2 emission value, so there is no change to the CO2 based taxation systems in the short term. This includes vehicle tax (VED) and company car tax (BIK).

Zemo Partnership is working with a wide range of government departments and stakeholders to assess the impact of regulatory changes on taxation bands but it is not expected that any structural changes will be made before 6th April 2020.

Timetable of Changes


From 1st September 2017  - New car models approved using WLTP.

  • Taxation continues to be based on NEDC CO2 emission figure.
  • Car labels and printed marketing material show NEDC fuel consumption and CO2 values, as well as electricity consumption and electric range.

From early 2018 - WLTP data available for a range of vehicles

  • Zemo Partnership (as LowCVP) publishes consumer guidance with coordinated industry supported approach
  • Using new WLTP data, proposals for policy transition begin to be developed

From 1st September 2018 - All new cars produced have WLTP information available.

  • Taxation continues to be based on NEDC CO2 emission figure.
  • Car labels and printed marketing material continue to show NEDC fuel consumption and CO2 values.

From 1st January 2019

  • Consumer information will show WLTP fuel and electricity consumption values plus electric ranges. The NEDC CO2 emission value will continue to be presented, the WLTP CO2 value will not be shown.

From 1st April 2020

  • Taxation and CO2 related policy switches to WLTP CO2 emission figures.