Now that almost a week has passed it is perhaps appropriate for calmer reflection on the controversy surrounding VW.

Most people will be aware by now that VW promoted its diesels in the US as being ‘green,’ but also secretly installed elaborate software in the cars’ engine management system to optimise emission abatement over performance whilst under lab tests, then reverting to optimising performance over abatement when out of test.

Emissions limits are of course a good thing, especially for NOx as it is implicated in numerous health issues including asthma. The Daily Telegraph reports that 12,000 deaths a year in the UK could be avoided if the car industry met its targets.

For emissions limits to be effective the lab test should be reflective of real world driving conditions otherwise it is rather pointless setting limits for NOx, particulates and other parameters that can only be met in the lab. Cars are used in the real world, not the lab.

As yet we do not know whether other manufacturers have also cheated, but so far it just seems to be VW and its subsidiaries that used the same engine technology (Audi and Seat).

So what should be done? Why not abandon lab tests and take cars at random and subject to real world driving over thousands of miles to establish the real emissions performance. This is exactly what is done with stack emissions testing. The claims of the manufactures of boilers or thermal oxidisers are not taken into account by the regulators, instead periodic monitoring is carried out on the stacks under real world conditions by contractors such as ourselves and with additional checks by the regulator. And if there are breaches of the emissions limits, then there are fines. Cars should not be any different.

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