Emission impossible?

Everyone knows about climate change and it’s a real drag. All of a sudden most of the things we liked doing are considered wrong. Some people even say we have to give up cars but that’s crazy talk isn’t it?

With around 70 million new cars produced each year around the world and a total of about  1.4 billion cars, trucks and buses in use it could be that there really is an issue. In New Zealand where we know our small population has a small relative contribution to climate change (don’t we?), motorisation rates are among the highest in the world. Our level of vehicle obsession is similar to the USA with around 82 cars per 100 people, so we make a disproportionate contribution of greenhouse gases as a nation with our personal transport decisions. But hey, technology will see us right, right?

It’s sometimes hard to avoid the inference that most new tech is directed towards getting us to buy more stuff, but manufacturers surely recognise the new environment reality and the marketing benefits of getting on board with the new way our planetary systems are heading. Car makers are surely developing vehicles with lower greenhouse gas emissions, because governments around the world have committed to reducing the primary causes of anthropogenic climate change. Besides those commitments, we car buyers are surely exerting our influence by demanding fuel-efficient cars that can save us money on fuel and save the environment. And it seems to work; CO2 emission ratings for new cars are coming down.   

Average CO2 emissions per km from new passenger cars in Europe. Naturally there is lots of variation across models and among countries (reflecting fleet composition), but the encouraging downward trend pre-empted the European emission limit of 130g CO2 per Km set in 2015. Yellow starts show target levels.

It turns out that manufacturers have been extremely responsive to the grown public and commercial pressure for better fuel economy giving us more kilometres per litre and so less pollution per kilometre. The figures that car sales people quote to us are encouraging and certainly allay any anxiety we had about justifying that big, new, shiny vehicle replete with all the extras.

Unfortunately, the official emission performance statistics (so-called type approval) on which we might base our decision of what vehicle to buy, and from which governments might infer success of policies directed at reducing emissions, are misleading. That’s putting it mildly. When you buy a car that that is stated to yield X g of CO2 per kilometre you’d be forgiven for assuming you will be producing about X g of CO2 for each kilometre you drive it.

Let every eye negotiate for itself
And trust no agent, for beauty is a witch
Against whose charms faith melteth into blood.

William Shakespeare: Much Ado About Nothing

Combining data from 14 different sources, from eight countries and more than 1,000,000 light vehicles it is clear that in 2001, the approved emission specifications were about 9% below the real-world situation (above).  That there was a difference is not hugely surprising because the way we drive our cars (compared with the test conditions) has a big effect on how efficient they are in real terms. What is of much, much greater concern is that in subsequent years the discrepancy has got bigger. Overall, by 2017 the difference between approved emission and real world (what happens when you drive) emissions increased steeply to around 45% (ICCT 2017).

Divergence between type-approval and CO2 emissions measured by Spritmonitor.de

One of the contributory data resources considered 148,000 German built passenger cars that came off the production lines between 2001 and 2016. Using three example years and considering the range of emission discrepancy scores from different cars makes the scale of the problem very clear. At the start of the millenium, actual emissions from cars were close to specification, just 7% higher on average. At this time the spread of discrepancy scores (the relative difference between promised and realised emissions) was fairly narrow and included some instances where measured emissions were lower than expected. However, in the years since, the average deviation has increased and so has the range of the scores. In 2016 for example with an average discrepancy of 38%, few cars had measured emission levels the same or less than expected. Some showed a difference between stated and measured emissions of more than 80%.

What has happened? Despite all the commitments to GHG emission reduction (e.g. in NZ) and all the technology under the bonnet of modern cars, we are actually doing worse at managing the problem. Currently the evidence indicates that the official GHG emission values are the source of the discrepancy. It is easy to see why, as the world population becomes increasingly aware of, and justifiably concerned about, anthropogenic climate change, we can imagine that car manufacturers might benefit from ‘optimistic’ emission statistics. Car sales are increasingly likely to reflect GHG emission data, and it is getting easier to find that information.

You will have spotted that the discrepancy between expected and real work emissions might be a curious artefact that hides a positive story. Perhaps emissions in real terms (rather than percentages) are so small that the inaccuracy hardly matters; after all 40% of 1 (0.4) is still smaller than 7% of 10 (0.7). But no, in real terms the official data indicate that, on average, new cars with combustion engines in Europe produced slightly more CO2 per kilometre (118.5 g) in 2017 than in 2016.

Although most manufactures were, officially, meeting the current European target of 130g/km this was a soft target and a long way from the 2021 EU target of 95g/km. If you take into account the mismatch between official CO2  emissions and real-world data, that showed in 2016 an average discrepancy of 45%, the supposedly achieved 118.5g/km translates to 171g/km (on average), which is above the 130g/km target.

So you have to ask yourself: are car manufacturers trying to avert planetary disaster or are they selling stuff? In the end the responsibility falls to us as individuals, and while the reality of our slide toward the operating limits of our world feels like too much to deal with, and the necessity to change your priorities and behaviour feels like somebody is getting one over on you, it is in fact wonderfully liberating. It is, now, not only okay to not follow the crowd, but the socially and environmentally responsible thing to do.

Steve Trewick

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