Question

How does the &#x27;Interpolation Family&#x27; concept allow manufacturers to determine CO2 emissions for multiple vehicle configurations without performing a separate test for every single variant?

Accepted Answer

The Interpolation Family is a regulatory framework under the Worldwide Harmonized Light Vehicles Test Procedure that groups vehicles with similar technical characteristics into a single family to streamline CO2 certification. To use this method, a manufacturer must select two specific vehicle configurations from the family: the Lowest CO2 vehicle, which is the lightest and most aerodynamically efficient version, and the Highest CO2 vehicle, which is the heaviest and least aerodynamically efficient version. Both of these extreme configurations must undergo full physical laboratory testing to establish their precise CO2 emission values. Once these two data points are established, the CO2 emissions for all other configurations within that family, which fall between these two extremes, are determined through a mathematical calculation known as interpolation. This calculation creates a linear relationship based on the mass, aerodynamic drag, and rolling resistance of the specific vehicle variant compared to the tested extremes. By using this interpolation line, manufacturers can accurately calculate the CO2 emissions for every intermediate variant without having to physically test each one, provided the intermediate vehicle shares the same engine, transmission, and emission control systems as the tested family members.

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How does the 'Interpolation Family' concept allow manufacturers to determine CO2 emissions for multiple vehicle configurations without performing a separate test for every single variant?