The National Emissions Test Cycle (NEDC) is a standardized laboratory test used to measure the emissions and fuel consumption of vehicles. It was first introduced in the 1980s and was widely used in Europe until it was replaced by the Worldwide Harmonized Light Vehicles Test Procedure (WLTP) in 2017 [1]. The NEDC was designed to simulate typical driving conditions in Europe and consists of a series of laboratory tests that measure a vehicle’s emissions and fuel consumption under controlled conditions. In this article, we will discuss the NEDC in detail, including its testing procedures, limitations, and how it compares to the WLTP.
How the NEDC Works
The NEDC consists of two parts: an urban driving cycle and an extra-urban driving cycle. The urban driving cycle simulates city driving conditions, while the extra-urban driving cycle simulates highway driving conditions. The test is conducted on a chassis dynamometer, which is a device that simulates the resistance of the road. During the test, the vehicle is driven through a series of predetermined speed and acceleration profiles, and its emissions and fuel consumption are measured [5].
The NEDC measures three types of emissions: carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx). It also measures carbon dioxide (CO2) emissions and fuel consumption. The test is conducted with a fully warmed-up engine, and the vehicle’s air conditioning system is turned off [1].
Limitations of the NEDC
While the NEDC was a significant step forward in measuring vehicle emissions and fuel consumption, it has several limitations. One of the main limitations of the NEDC is that it is conducted under laboratory conditions and does not reflect real-world driving conditions. The test does not take into account factors such as traffic, weather conditions, and driving behavior, which can significantly affect a vehicle’s emissions and fuel consumption [3].
Another limitation of the NEDC is that it does not consider the impact of optional features on a vehicle’s emissions and fuel consumption. For example, a vehicle with larger wheels or a more powerful engine may have higher emissions and fuel consumption than a base model, but this is not reflected in the NEDC test results [1].
How the WLTP Compares to the NEDC
The WLTP is a new testing procedure that was introduced in 2017 to replace the NEDC. The WLTP is designed to provide more accurate and realistic measurements of a vehicle’s emissions and fuel consumption under real-world driving conditions. Unlike the NEDC, the WLTP takes into account factors such as traffic, weather conditions, and driving behavior [1].
The WLTP also includes a wider range of driving conditions than the NEDC. The test consists of four parts: low, medium, high, and extra-high speeds. The average speed during the test is also higher than the NEDC, increasing from 34 km/h to 46.5 km/h [1].
Furthermore, the WLTP addresses the issue of optional features by testing entry-level models and range-toppers alike. This means that the test results reflect the emissions and fuel consumption of a vehicle with all available options [1].
The Importance of Accurate Emissions Testing
Accurate emissions testing is essential for reducing air pollution and improving public health. Vehicle emissions are a significant source of air pollution, and reducing them can have a significant impact on air quality. Accurate testing also helps consumers make informed decisions about the vehicles they purchase and encourages manufacturers to develop more fuel-efficient and environmentally friendly vehicles [2].
Conclusion
The NEDC was a significant step forward in measuring vehicle emissions and fuel consumption, but it has several limitations. The WLTP is a new testing procedure that provides more accurate and realistic measurements of a vehicle’s emissions and fuel consumption under real-world driving conditions. Accurate emissions testing is essential for reducing air pollution and improving public health, and the development of new testing procedures such as the WLTP is an important step forward in achieving these goals.