Last updated: January 2016
Car Companies and Carbon Emissions
Since EU rules have demanded it, we have become used to car companies displaying fuel consumption and CO2 emission values on all promotional materials. In the UK, cars with emissions lower than 100 g/km pay no car tax, and those with higher emissions pay gradually increasing amounts up to £1100 for the worst gas guzzlers.
With nearly 70% of people now buying new cars with claimed lower emissions, more miles per gallon (mpg), and therefore lower tax, it is clear that small differences in these figures can be important in driving sales. 
But as well as coming up with better design innovations to meet emissions targets, it appears that most companies are also cheating the spirit, if not the letter, of the tests as well.
Independent testing by European consumers’ associations and other third parties is simply unable to replicate the claimed mpg performance in almost all cases. [2,3]
Tricks like removing wing mirrors, over-inflating tyres and taping up doors can be combined with test conditions which do not mimic real-world driving scenarios to achieve impossibly flattering results. [2,3]
In the words of the campaign group Transport & Environment (T&E), "The gap between test results and real world performance has become a chasm, increasing from 8% in 2001 to 31% in 2013 for private motorists and without action it is likely to continue to grow to over 50% by 2020.”
What can we do?
As car buyers it is necessary to take claimed emission figures with a pinch of salt. T&E have helpfully produced the table above showing how badly each manufacturer performs on test manipulation. If, for example, you are thinking about buying a VW, you can take its claimed CO2 emissions and multiply them by 1.28 to get a more likely performance value. Consumers’ associations and the nextgreencar.com website also display different figures for real and claimed mpg (and therefore emissions).
People may even choose to avoid the worst performers – Daimler, BMW and Ford.
In the longer term, regulators, being well aware of this problem, are proposing to introduce a new test in 2017 to try to make this kind of cheating more difficult (the World Light Duty Test Cycle). In a further display of crass selfishness, car makers are opposing the introduction of the new test and want to see a long delay because it will reduce their ability to manipulate test results in the future.
Consumers need to support groups like the UK Consumers’ Association and T&E who are calling on regulators to stand firm.
A social responsibility issue
In 2015, none of the car companies are, in public, climate change deniers. Their CSR reports talk enthusiastically about their plans and research around lower emission car designs. However, cheating the emissions tests flies in the face of claims to take these issues seriously.
The CO2 targets for the industry, set by the EU, and the car tax regimes set by governments, are there for a purpose. We have all agreed collective targets for CO2 reduction by 2020 and 2050 because without them the conditions for life on this planet become impaired.
We can see why they are cheating. VW was reported as saying that each gram of CO2 emissions it is required to reduce costs it €100 million,  and we have seen above how consumers are favouring more economical models. It hurts companies short term profits not to cheat – and in the longer term, the fate of the biosphere seems to take a second place.
It is hard not to conclude from this that purely for-profit companies operating in this area are not really fit for purpose in the 21st century. Responsible companies should choose voluntarily to provide real world data now. It is a testament to how much value they place on human survival that they have not done so.