Fuel Efficiency & WLTP: What Does it all Mean?

WLTP stands for ‘Worldwide Harmonised Light Vehicles Test Procedure and is the name of the testing process for measuring fuel economy, electric driving range, and emissions in new cars. To put it simply, WLTP is how the range, MPG and emissions are calculated for any new car.

But what does the test consist of? How do manufacturers get to the result? And how accurate is it? We have collected everything you need to know about the testing process, and what it means for your car.

When comparing pre-2017 mpg figures to more current ones, it may seem that fuel economy has somehow got worse, as many older vehicles boast impressive statistics on paper. This, in fact, is due to the increased accuracy in relation to real world driving that WLTP offers when compared to its predecessor. The previous test was entirely lab based, allowing for vehicles to run much more efficiently than they would in the real world. WLTP runs tests at a number of different speeds for a longer period of time (30 minutes, instead of the previous 20) as well as providing a more realistic temperature and more realistic acceleration/deceleration.

WHAT IS THE DIFFERENCE BETWEEN WLTP AND ITS PREDECESSOR?

 One of the major factors that helps the accuracy of WLTP is the mandatory usage of it across all passenger vehicles, and how it can be tailored to each vehicle accordingly, for example, gear shifts depend on the gear ratio of that specific vehicle, while in the older test, shifts were performed at a set speed, which suits some vehicles better than others, and does not reflect the way a large number of cars are driven. The varying speeds also provide results that are much more likely to match your individual driving. The reality of fuel economy is that it varies greatly, depending on the journeys you are doing. WLTP tests 4 different speeds, set as urban, suburban, main road and motorway.  WLTP also tests the same vehicle with different optional extras on. The major benefit of this for the consumer is that they are now able to see how different trim levels may affect the economy and emissions of a certain car.

HOW IS WLTP MEASURED?

The WLTP test cycle is performed in a lab set to 14°C, which better reflects the UK climate than the previous 20-30°C and consists of the car being driven for 30 minutes, equating to around 14 miles. In these 30-minute cycles, the car is driven at four different speeds, which, as previously mentioned, represent urban, suburban, main road and motorway. The actual speeds of these tests are 35mph, 47mph, 60mph, and 81mph. The figures from these tests are then averaged out, which provides the car with its combined mpg figure, and a realistic average for most people. Some manufacturers will provide the full results, with the score for each individual test, however this is not mandatory, so you may only be able to see the combined figure in some cases.

DOES WLTP MEASURE ELECTRIC RANGE WITH THE SAME TEST?

Yes. Electric range is measured with the same test as traditional ICE vehicles. This helps make the direct comparison for efficiency between electric and ICE much more straightforward and helps legitimise the results of both drivetrains.

WHAT ELSE DOES WLTP MEASURE?

One of the biggest reasons that WLTP was implemented was to help different countries and regions compare pollutant and CO2 emissions more accurately. Fuel economy and CO2 emissions are directly related, as the more fuel your vehicle uses, the more CO2 it emits. One way the CO2 calculation directly affects you is through tax, as the WLTP figures are used to figure out the tax rates the apply to each car. The tests and requirements for CO2 emissions are getting more and more strict, meaning that many vehicles are becoming more expensive to tax. This is one of the benefits you get from an electric vehicle, as their zero CO2 emissions result in no tax.

SO HOW ACCURATE IS WLTP?

WLTP is undoubtedly a much-improved test to in comparison to the previous procedure and provides a much more realistic figure for a car’s economy in real world driving. The more rigorous and thorough tests performed help cover a wider range of driving behaviors and styles, while the previous test would tend to overinflate the economy figures that could be achieved in the real world. At the very least, even if you do not trust the figures the WLTP provides, they are still comparable to every other vehicle that has undergone the same test. With the previous testing, certain vehicles would perform much better than others due to it being much less thorough. With the current process considering different speeds, more realistic acceleration/deceleration, and more realistic climate, it is much easier to directly compare the results of two different vehicles.

If you are looking for further information on WLTP or would like to book a test drive in a new Peugeot electric vehicle at one of our Simon Bailes Peugeot showrooms, contact us here. Our showrooms are located in Northallerton, Stockton and Guisborough, covering the North-East and Nationwide.