Continuous Vehicle Emissions Monitoring (CVEM)

Continuous Vehicle Emissions Monitoring

An alternative to vehicle type approval regulation:
Continuous Vehicle Emissions Monitoring (CVEM)

Working in partnership, Next Green Car and NXP Semiconductors, propose the use of Continuous Vehicle Emissions Monitoring to complement laboratory and 'real driving' emissions testing.

While the initial vehicle emissions standards (which form part of type approval) were highly successful in reducing real-world vehicle emissions by an order of magnitude, the rate of reduction has recently slowed. There is evidence that some pollutants, in particular NOx, have not in fact measurably improved since 2006.

It is now widely accepted that the current approach is not fit-for-purpose as the test cycle (currently NEDC) does not adequately represent real-world driving conditions. Even its replacement, the WLTP due in 2017, will only marginally reduce, not eliminate, the discrepancy between test and real-world emissions.

A second development, the introduction of Real Driving Emissions (RDE) testing, may also have limited impact as its primary aim is only to reduce the permitted exceedance of emissions over maximum levels as specified in the legislation.

An alternative or complementary approach to future type approval testing is to introduce a system of Continuous Vehicle Emissions Monitoring (CVEM), which utilises existing On-Board Diagnostic (OBD) sensors to monitor emissions, and export this data to a central off-board server for reporting purposes.

Modern vehicles are already equipped with sensors that monitor exhaust emissions including: CO2, NOx and (to an extent) particulates. With the on-going evolution of vehicle connectivity, by 2020 the majority of light-duty vehicles will be capable of transferring this data to a central server from where it could be collated and used for regulatory use. The European eCall Directive already requires that all cars from April 2018 must have a mobile data link.

In addition to laboratory and RDE testing, CVEM will offer three new functions: (i) Enable regulators to monitor national and local fleet emissions in real-time; (ii) Permit more accurate auditing of fleet emissions in place of emissions modelling; and (iii) Provide transparency for consumers, whose levels of confidence have been challenged with the VW emissions scandal.

For vehicle regulators not to adopt monitoring technologies based on the latest data platforms would be a missed opportunity and would undermine future attempts to control emissions and promote cleaner vehicle technologies. Now is the time, therefore, for regulators to develop and implement a system of Continuous Vehicle Emissions Monitoring using on-board sensors and digital communication platforms as an integral part of future vehicle type approval.

Download NGC-NXP white paper [pdf]: An alternative to vehicle type approval regulation: Continuous Vehicle Emissions Monitoring (CVEM)

More info: Dr Ben Lane, Next Green Car, 0117 929 8855,

References: [1] NEDC:, [2] ICCT:, [3] WLTP:, [4] RDE:, [5] eCall:

Lead image courtesy of Continental AG

Chris Lilly

Author:Chris Lilly
Date Updated:10th Jul 2018

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