Emission impossible? Not any more. Soon we’ll know which cars REALLY are the cleanest

Image of Alisdair Suttie
Author: | Updated: 31 Mar 2017 16:11

Emissions are something most of us will consider to one degree or another when selecting our next car. Whether that’s because we want to minimise the amount of tax we pay or for more environmentally friendly reasons, what comes out of the tailpipe is important.

But how do we know exactly what is being emitted?

Scenes likes this will soon be a thing of the past

Scenes likes this will soon be a thing of the past

Until now, we’ve had to go by what car companies tell us with their official figures. Of course, those numbers have taken a serious knock in credibility in the wake of the Volkswagen diesel scandal. That’s why the Mayors of London and Paris have got together to reveal an on-going emissions scoring system for residents of their respective cities.

Announced at the C40 Air’volution event in Paris, a database of all the gasses that emerge from car exhausts will be created. From there, this information will be available to all drivers so they can establish which cars are the cleanest and which are the worst.

It’s set to go live in the autumn and will be a free-to-access tool that Mayor Sadiq Khan says is there to address the consequences of official emissions testing. According to the Air’volution event, official tests underestimate the effects of ‘on-road’ driving which has led to some cars producing 12 times as much nitrous oxide on the road than in the laboratory.

Photo credit: Paris/H.Garat

Sadiq Khan at the Air’volution event

This database is the first major step towards the introduction of the Real Driving Emissions (RDE) tests set to come into force in 2021. Even then, car makers will have a period of grace where their products will be allowed to exceed the limits by up to 50%.

British company Emissions Analytics already measures real-world vehicle emissions and has compiled its own independent statistics. Nick Molden, CEO and founder of the company, says: “Both the Mayors of London and Paris have identified that vehicle emissions in the real world are a major contributor to the current air quality issue.

“This validates the work of Emissions Analytics, which has been recording on-road vehicle emissions for six years. We are delighted that both cities will be using our data to help inform consumer decisions.”

The current New European Drive Cycle (NEDC) is unfit for purpose

The current New European Drive Cycle (NEDC) is unfit for purpose

So, before long, we will be able to find out just how clean or otherwise many new cars are when driven in a normal fashion instead of being hooked up to sensors in test conditions. This begs the questions of why bother with the official tests at all if they cannot be trusted to be accurate.

Taking the subject of cheat devices out of the equation, as we cannot account for those who seek to circumvent legislation here, the official tests work in one simple way. That is they provide a level playing field where all cars are tested in the same way and in the same conditions, which means we can draw some comparisons between different models.

However, this is also where the mandated tests fall flat as there are so many variables that dictate how much pollution is emitted from a vehicle’s exhaust.

How we drive dictates our emissions

How we drive dictates our emissions

For example, the tests used at present were devised in the 1980s when vehicle emissions were a minor concern. The procedures and outcomes now are simply not fit for purpose as car design has changed so radically in the intervening 30 years. Now, most cars have air conditioning, heated rear windows and many other electrical features that can be switched off in a test to give the best result.

Yet we all use these functions every day and they put more demand on the engine, which in turn creates more emissions.

There is also the variability in driving styles between different users, even when they are in identical cars or even the same car shared by more than one driver. Not only are there personal fluctuations in how we drive, there are also environmental changes that have altered how cars perform in the real world compared to 30 years ago.

Congestion continues to grow and put a strain on things

Congestion continues to grow and put a strain on things

For instance, congestion has grown in almost every major urban area so we spend more time stationary in the car than ever before. As not every car has a stop-start system fitted, and not every driver makes use of it, we cannot say if this has been countered by improved technology.

There are also more company vehicles on the road of all types and many have their fuel paid for by an employer, so the person driving the car or van or truck may well not be so concerned about using it in the most efficient manner. And then there’s the huge rise in the number of diesel-powered cars on the roads due to previous government incentives to swap to this fuel.

So, as you can see it’s far from clear-cut when trying to work out the emissions of a car in a laboratory compared to what actually comes out of the exhaust when it’s being driven by a human.

PHEVs like the Mitsubishi Outlander can only do so much

PHEVs like the Mitsubishi Outlander can only do so much

For us, the people who lease cars and use them every day, the new information that will be available soon from the offices of the London and Paris Mayors will be invaluable. This gold dust data will help us to make far more informed choices about the cars we decide to pay for and use every day.

It may also have an impact on the amount we pay as leasing companies and car makers will be watching the results even more keenly than you and I. Should a car prove to be noticeably better or worse than the claims from its manufacturer, it could spell success or ruin for its sales prospects.

Of course, we must bear in mind that this new data will be taken in a city environment, so there is the chance it will be skewed to a small degree because of the geographical location of the measurements.

M1 motorway flickr underbean2

Even so, this is a much better way to decide which cars are the cleanest and which are the most polluting, especially as cars tend to be at their environmental best when on the open road of a motorway.

An independent, repeatable and broad-based set of facts and figures is to be welcomed, particularly when it will be readily available to all drivers so we can make the right decisions on our next vehicle choice.

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