Nature has posted a good layperson's backgrounder on the VW pollution exploit. (outside their usual paywall)
The California Air Resources Board has posted a letter addressing the emissions testing loophole that VW exploited. Specifically the test is now much closer to the real-world and the specific details are not revealed to the manufacturer before time. The EPA posted a similar letter.
But the UK lobbied for car makers to be allowed to exploit flexibilities such as externally charging their batteries to full before testing. The Department for Transport also argued that the best available technologies should be shunned in favour of outdated ‘inertia classes’, which involve manually adding 100 kilo weights to the car to see what effect greater weight on the amount of CO2 the car pumps out.
Research by the International Council on Clean Transportation has found that car manufacturers often game these tests by optimising test car performances at one pound below the desired inertia class.
Germany went further than the UK, calling for the tests to be conducted on sloping downhill tracks, and for allowing manufacturers to declare a final CO2 value 4% lower than the one measured. France supported all the proposed loopholes, bar the 4% lower CO2 value.
Together, these flexibilities would allow some 14% more CO2 to be emitted than EU regulations permit, according to an analysis by T&E. CO2 emissions contribute to climate change, while the nitrogen oxides (NOx) that VW rigged tests for are primarily a cause of local air pollution.