WLTP Explained: 2021 update

The motor industry is full of jargon and technical lingo, which often makes it hard to understand exactly what’s going on. Luckily, we’re here to help you make sense of it all.

You may have seen the acronym ‘WLTP’ flying around, particularly if you’ve been looking at purchasing a new vehicle, but what is it? Read on for the lowdown on WLTP and how it might affect you.

What does WLTP mean?

WLTP stands for Worldwide Harmonised Light Vehicle Test Procedure – yes, that’s a four-letter acronym for a six-word name!

Basically, it’s a lab test that applies to all new vehicles registered since September 2018, to check how they perform in everyday driving conditions.

In fact, it also applies to any new model that’s been introduced to the market since September 2017. The sixth-generation Volkswagen Polo, for example, was launched in late 2017, so would’ve been required to undergo WLTP testing under the new rules.

The tests are run by independent testers on vehicles that are provided to them by manufacturers, long before that manufacturer sells that model in its showrooms. Don’t worry – you won’t ever have to deal with WLTP tests yourself!

car exhaust fumes

What is the WLTP cycle?

For a long time, all new vehicles have been subject to the NEDC test procedure, also known as the New European Driving Cycle. It was designed to test and assess a passenger vehicle’s emissions and fuel economy.

Last revised in the late 90s, the NEDC was widely criticised for delivering figures that weren’t achievable in the real world. That’s not to say the tests were intentionally misleading; they just weren’t exactly reflective of how a car would be used on a day-to-day basis by an average driver.

The WLTP test has been totally redesigned to provide a better representation of ‘real world’ CO2 emissions and fuel consumption.

Basically, the WLTP test takes place over a longer distance than the outgoing NEDC test, using higher top and average speeds, and lasting a greater amount of time. And unlike the NEDC test, the impact of all available optional equipment – such as bigger wheels or panoramic sunroofs – is considered in the WLTP cycle.

How does WLTP affect me?

WLTP was introduced so that the driving figures that manufacturers publish are more reflective of real world driving. That means that the figures displayed on sites like ours for emissions and fuel economy should be more accurate.

How might that affect you? Well, it’ll help you make a more informed decision when it comes to purchasing your next vehicle, as you’ll be able to better understand how much a vehicle will cost to run on a day-to-day basis. Maybe a particular car on your shortlist will cost you a bit more a month to buy, but if it’ll save you on the cost of fuel over a less expensive model, then perhaps it’s worth it.

As well as fuel consumption, of course, WLTP will determine the CO2 emissions for a particular vehicle, and it is those CO2 emissions that determine how much VED – or road tax – a vehicle is subject to. From April 2020, the vehicle tax system in the UK has used WLTP-only figures, moving away from the NEDC figures for good. From April 2021, the first-year tax rate will be increasing for vehicles in VED bands D-M.

New VED bands for 2021/22

CO2 emissions (g/km)Standard rate (2021-2022)
Up to 100£0
101-110£20
111-120£30
121-130£130
131-140£155
141-150£170
151-165£210
166-175£250
176-185£275
186-200£315
201-225*£340
226-255£585
Over 255£600

Which vehicles will be affected by WLTP?

Any new model introduced since September 2017 and any new vehicle registered since September 2018 has been subject to WLTP testing.

Of course, that means any vehicle that is already on the roads before that 2018 date hasn’t undergone the WLTP testing, so its older NEDC-tested figures will remain applicable when it comes to deciding road tax.

What else do I need to know?

There’s another test called the RDE, or the Real Driving Emissions test, which measures the amount of Nitrogen Oxide and other pollutants emitted by a passenger vehicle.

The RDE test is not meant to replace or overtake the WLTP test, but it is supposed to help provide a bigger, more complete picture about the environmental impact of each new vehicle.

During the RDE test, a vehicle is driven in a variety of realistic, real-world conditions, including different altitudes as well as in a range of temperatures.


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