Emissions tests explained

A new testing procedure designed to produce more realistic figures for car emissions and fuel consumption, WLTP replaces the now outdated NEDC. Since September 2018, WLTP has been the new, mandatory way for measuring fuel economy and CO2 emissions on all new cars rolled out.

If you want to know more about how WLTP works and what it means for you if you’re looking to lease, read on. But first, here’s a little background on emissions testing.

Emissions tests explained

Both the WLTP and the NEDC are emissions testing procedures. These are designed to replicate, as much as possible, how a car is typically used on the road. The WLTP is the latest set of standards while the NEDC was its predecessor.

What was NEDC?

NEDC stands for the New European Driving Cycle. But while the word ‘new’ includes its name, it’s been around since the 1980s. In fact, the NEDC was last updated in 1997, so it’s not very new at all, at least by today’s standards.

What is WLTP testing?

On the other hand, The WLTP or Worldwide Harmonised Light Vehicle Test Procedure came into discussion in 2008. The initial plan was to launch it in 2023. However, the Dieselgate scandal persuaded the European Commission to expedite its preparation, leading to the WLTP being launched in 2018.

Mercedes-Benz Emission Test

What is the difference between WLTP and NEDC?

On paper, the WLTP might look virtually identical to the NEDC process; however, there are some big differences between the two. Not only does the WLTP test take 30 minutes, which is 10 minutes longer than the NEDC, but it also takes up to 5 days to process. The distance covered is also longer at 23.25 km compared to the original 11 kms.

Here’s a comparison of both testing procedures:

 WLTPNEDC
Test cycle: Dynamic cycle Single test cycle
Cycle time: 30 minutes 20 minutes
Cycle distance: 23.25 km 11 km
Driving Phases: 4 phases: 52% urban-based, 48% non-urban based driving 2 phases: 66% urban-based, 34% non-urban based driving
Average Speed: 46.5 kph 34 kph
Maximum Speed: 131 kph 120 kph
Influence of Optional Equipment: Some considered Impact on fuel performance and CO2 not considered
Gear Shifts: Gear shift points vehicle dependant Fixed gear shift points

How does WLTP affect me?

From creating more transparency around car emissions to helping you make more informed leasing or buying decisions, there are a lot of ways the WLTP could affect you.

For one, it’s made more information available, from best-case figures for each model in a range to 5 different cycles (low speed, medium speed, high speed, extra high speed and combined) you can choose from to check your typical journeys against.

All figures made available by the WLTP coincided with changes to CO2-related taxation on 1 April 2020. That should help consumers choosing a new vehicle based on the tax benefits available to low and zero-emission vehicles.

The downside, of course, is that it will result in higher taxation on vehicles that aren’t RDE2-compliant. The hope, however, is that in the longterm a transition to WLTP will mean a fairer, greener and more transparent auto industry.

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