Tough new real-world economy and emissions testing comes into force

Tough new real-world economy and emissions testing comes into force
Tough new real-world economy and emissions testing comes into force

The way new cars are tested for fuel economy and emissions has been overhauled for the first time in 20 years.

This month sees the introduction of two new tests which aim to more accurately measure how much fuel vehicles burn and the levels of air pollution they emit.

The much-criticised New European Driving Cycle (NEDC) laboratory test, which was introduced in the 1980s and hasn’t been updated since 1997, has been replaced with Worldwide Harmonised Light Vehicle Test Procedure (WLTP) lab assessment and a real-world driving element – the Real Driving Emissions (RDE).

The new tests are being rolled out partly in response to the Dieselgate scandal which saw millions of VW Group cars fitted with electronic “defeat devices” designed to return unrealistically low emissions results under lab conditions. They also come after years of complaints that the official fuel economy figures are often wildly inaccurate – something car makers blame on the NEDC testing process.

“These new tests will soon give consumers emissions performance information that is far closer to what they experience behind the wheel”

Mike Hawes, SMMT

Under the new WLTP, the test conditions are faster, longer and more dynamic, covering a broader range of driving conditions and road types. It includes a greater range of vehicle and engine speeds, engine load, gear changes and temperatures. The new test also takes into account the weight and aerodynamic effects on CO2 emissions of optional equipment such as larger wheels and air conditioning.

Real-world experience

Much of the criticism of laboratory testing is that it can never realistically reflect the huge variance of driving conditions and situations experienced on the road. A Government study last year found that some Euro 6-compliant diesel cars emitted six times more nitrogen dioxide in real-world conditions than in lab testing.

The RDE is a response to this and aims to force car makers into engineering vehicles that are less polluting in the real world.

Under the RDE vehicles are driven on public roads for at least 90 minutes while fitted with portable sensors that connect directly to the exhaust pipe and measure emissions of carbon monoxide, carbon dioxide, nitrogen oxides and particulate matter.

SMMT

The new tests have been developed by European regulators working with the motor industry.

Mike Hawes, chief executive of the Society of Motor Manufacturers and Traders, said, “We welcome this challenging new regime, which will provide hard evidence that the industry’s ongoing investment in ever more advanced technology is delivering on air quality goals.

“Combined, these new and demanding tests will soon give consumers emissions performance information that is far closer to what they experience behind the wheel – and inspire greater confidence that the new cars they buy are not only the cleanest, but the most fuel efficient ever produced.”

The new testing regime came into force on September 1 and by September 1, 2018, all new cars on sale will have undergone WLTP testing. By September 1, 2019, all will have undergone the full RDE testing. However, the old NEDC figures will still be used to calculate European fleet average emissions until 2020 and used in the short term for the purposes of UK vehicle excise duty rates.

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