What are the NEDC fuel economy tests?

Get up to date with NEDC fuel economy tests, including how they were conducted, what was wrong with them and how they’ve been replaced

Exhaust emissions

Until recently, all new cars had their fuel economy and emissions tested under the New European Driving Cycle – or NEDC – system.

The first uniform European economy and emissions testing procedure launched in 1970. It evolved into NEDC, which was last updated in 1997.

• Everything you need to know about VED road tax

Now, NEDC has been replaced by a newer set of tests – WLTP (Worldwide harmonised Light vehicle Testing Procedure), but NEDC figures still form the basis of company car tax calculations, for example, so they are still relevant for UK motorists.

What is NEDC?

NEDC is the outgoing pan-European method for assessing a car’s fuel economy and emissions.

Designed to represent the typical usage of a car in Europe, each test consisted of four repeated urban driving cycles and one extra-urban driving cycle.

With NEDC having not been fully updated for 20 years, though, and being widely criticised for producing fuel economy figures that weren’t easily achievable in the real world, its replacement was considered long-overdue by many.

Why is NEDC still relevant?

The way company car tax – also known as Benefit-In-Kind (BIK) – is calculated still involves the CO2 emissions of the car in question. This is an issue because the WLTP results give a higher CO2 reading than NEDC so a switch to them would increase BIK rates sharply.

In order to work around this and protect drivers of company cars from sudden, sharp tax increases, a system called CO2MPAS is used to convert WLTP CO2 readings into what is known as an NEDC equivalent.

While a car’s CO2 emissions will still increase as an NEDC equivalent compared with standard NEDC, they won’t be as high as they would be if left as a WLTP result, thus mitigating the tax increase for the driver.

For example, a car that emitted 107g/km of CO2 under NEDC might produce 137g/km under WLTP, resulting in a large increase to the BIK rate. If the figure were to be run through CO2MPAS, however, and turned into an NEDC equivalent, it might only be 117g/km, meaning the increase wouldn’t be as drastic.

• Everything you need to know about BIK company car tax

Another reason NEDC is still relevant is that cars registered between 1 March 2001 and 31 March 2017 have their Vehicle Excise Duty (VED) calculated based on the CO2 emissions, as do cars registered after 1 April 2017 for their first year of road tax. While cars currently on sale are required to go through WLTP testing, models no longer in production that were registered in this period will have their tax rates calculated from NEDC emissions figures, while post-April 2017 models that aren’t being built any more will for their first year too.

NEDC figures are also still displayed on parts of some manufacturers’ websites, although these will be replaced by WLTP data in time.

What has replaced NEDC?

NEDC has been replaced by WLTP, the purpose of which is to provide more realistic emissions and fuel economy figures that are achievable in real world driving.

The tougher new criteria has meant that many models currently in production now have worse economy and emissions data on paper, though their efficiency on the road remains unchanged by the new tests.

WLTP has also led to delays with some models, especially plug-in hybrids, as manufacturers have struggled to get their entire ranges recertified to the new rules.

Find out full details of the new WLTP emissions and economy tests here….

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