What is WLTP?

We know how the story goes – you buy a car that has an official fuel consumption figure of 65.6mpg, but find yourself managing just 52.1mpg all the time. It’s a drag and you’re paying out more than you expected. What gives?

Measuring these figures can’t be easy for the testers involved, but it’s hoped that it’s just about to get a whole lot easier.

For more than thirty years, the New Driving Cycle (NEDC) has been used to carrying out fuel economy and European new car emissions tests. As of September 2017, however, a new test has replaced the dated NEDC. It’s called the Worldwide Harmonised Light Vehicle Test (WLTP).

In case you were wondering what it’s all about and what it will mean for you as a driver and car owner, OSV has got you covered with our article all about the WLTP.

We’re going to take a look at:

What WLTP means and is
How WLTP works
How WLTP will impact you
The changes WLTP will make
When the changes will take place
How WLTP will impact car tax

Let’s get started …

What Is WLTP?

The Worldwide Harmonised Light Vehicle Test was developed by the European Union. It came into effect as of September 2017 and replaces the outgoing New European Driving Cycle test. It will measure CO2 emissions and fuel consumption from cars and vans.

It will also measure pollutant emissions and will introduce the kind of realistic testing conditions that the old NEDC test failed to do.

More on these changes later but first …

How does WLTP Work?

The aim of WLTP is to give you as a car owner a more realistic understanding of how your car performs. The new tests will make sure that lab measurements from now on are able to more accurately reflect the driving situations you face on a day to day basis.

In other words, the emissions and fuel consumption values displayed for brand new cars that are on sale will be a much more precise indication of what you will go onto achieve once you take the car onto the road.

Although both WLTP and NEDC take place in controlled conditions, the main difference is that WLTP will be testing cars with and without the optional extras that some buyers add. This is so that the chances of a more accurate result are increased.

Moreover, WLTP will be able to include faster speeds, and it will also take into consideration both deceleration and harder acceleration.

How Will WLTP Affect you?

When we weigh up our options for our next car, the main priority for a lot of buyers is fuel consumption.

But imagine if you bought a hatchback because – according to official figures – it returns 75mpg on average, only finding that, in real-world conditions, it barely scrapes 55mpg.

Epic fail.By being more accurate, the WLTP make the buying process much easier.

Financially, the WLTP won’t affect you too much – if at all.

The reason for this is that a vehicle’s performance isn’t going to be manipulated by the WLTP test. However, what might happen is that a car tested by WLTP and not NEDC might have a higher CO2 figure simply because the new test is more rigorous. This could create confusion.

For example, let’s say that a 2017 car that used the old NEDC test emits 100g/km of CO2. In 2018, the same car – but a brand new recently approved one – is tested by WLTP and is found to emit 120g/km of CO2. It’s only natural that a buyer will be tempted to purchase the slightly older model, right?

What Changes Will WLTP Make?


The NEDC driving cycle test was old and things needed changing. The WLTP test is focusing on more realistic conditions so that the true performance of a car is better measured before you make a purchase.

Here are the changes WLTP will make:

Test cycle be more dynamic
Cycle time will increase by 10 minutes
Cycle distance will more than double
Driving phases will be more dynamic – 48% non-urban and 52% urban
Average and maximum speeds will increase
Optional extras will be taken into consideration for the first time
Gear shifts will also be taken into consideration
Test temperature will be corrected from 20 to 23 Celsius.

When Will The WLTP Changes Take Place?

The important thing to note is that, while there will be changes taking place in regards to how a car’s performance is measured, the actual performance of a car won’t change.

Here is a timeline of when the WLTP changes will take place:

September 2017 – all-new model introductions are subject to Real Driving Emissions and WLTP type approval testing

September 2018 – Any new registration will have to comply with WLTP type approval

September 2018 – Any new light commercial vehicle will be made subject to Real Driving Emissions and WLTP type approval

September 2019 – Any new registration will have to comply with RDE testing

September 2019 – Any new registrations of light commercial vehicles be made subject to RDE testing and will have to comply with type approval under WLTP

How Will WLTP Affect Car Tax?

At the present moment, you don’t need to worry about changes to car tax.

The cost of car tax (or “Vehicle Excise duty”) is determined by a car’s CO2 figure. This is worked out during the first year of a new cars registration.

For all cars approved by WLTP, a number equivalent to what an NEDC test would have brought up will be added to the database – and will continue to be used for the foreseeable future. At a later date, the CO2 figure forecast by WLTP will replace the one forecast by the NEDC. That exact date is not yet known.

Once WLTP starts calculating vehicle tax, it won’t affect cars that are already registered. Only cars that are at that time unregistered will be affected.

Hopefully, WLTP makes more sense to you now. All you really need to know in a nutshell is that the new test will make measuring a car’s performance a lot easier. This means that when a car’s official fuel consumption figure is 65mpg, you can be a lot more confident that you’ll be returning 65mpg (or there or thereabouts on a regular basis).

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