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Preparing for the real world

Date: 18 August 2017   |   Author: Debbie Wood

The ageing New European Driving Cycle (NEDC) will finally be replaced in September 2017 with a new Worldwide Harmonised Light-Vehicles Test Procedure (WLTP), which ushers in a tighter and more accurate testing process, and aims to bring official mpg figures closer to what people achieve when driving in the real world.

This new test is expected to bring much-needed improvements to the way cars will be tested, and will produce more realistic CO2 emission figures and fuel economy data, but with it's introduction also comes a great deal of confusion.

What does it mean for taxation? Which cars will the new test be performed on? And what about those NOx emissions that are grabbing so many of the recent headlines?  

New testing

The NEDC has been around for over 30 years and its inability to represent real-world driving has long been known. Conducted in a laboratory at a set temperature of 20-30°C, engines are started from cold and cars loaded onto a chassis dynamometer with a pre-programmed 20-minute route that includes elements of idling, acceleration and braking at various speeds up to 75mph.

No lights, window wipers, music, or systems such as air-con and heated seats are on during the test, while the route has no periods of stopping that would represent congestion or traffic lights - there is also no luggage or passengers in the car. It's not only fuel economy figures that the test produces; it records CO2 emissions,  which are also found to be well off the mark in real-world driving.

The new WLTP will still be conducted in laboratory conditions like the NEDC, but will incorporate higher speeds, stricter measurements and more representative driving behaviour. Testing time will increase by ten minutes to half an hour and incorporate four phases instead of the current two. It will take into account vehicle mass, optional equipment, tyre rolling resistance class and aerodynamics. However, according to Nick Molden, CEO and founder of Emissions Analytics, it will still not be close enough to real-world driving.

"The main problem is that the WLTP is not that aggressive; it's still easier than normal driving and we think it will underestimate CO2 by around 20%. It's around 40% at the moment, so WLTP will halve the problem," he tells BusinessCar. From September 2017, WLTP will officially apply to new models that are introduced into the market for the first time and, in September 2018, all new car registrations in the EU will be applicable.

Real-world tests

Supplementing the WLTP in September will be a Real Driving Emissions (RDE) test and this two-and-a-half-hour test will measure pollutants including NOx and CO2, as well as record fuel economy. RDE tests will not replace the laboratory WLTP but will be additional to it, and the results will be published alongside the official figures to provide extra guidance for drivers and fleets.

Emissions Analytics has been conducting its own real-world tests since 2011 and was invited to join the working group when the new RDE test was created. Molden believes the new regulations are a big step forward but there are still some issues to overcome. "The new test will make things a lot better but it has two major problems," Molden says. "Firstly, the tests themselves will still be completed by the manufacturers; they will come up with their own route, which has to be designed to a set criteria, and then submit the numbers to the authorities - so, it's not really independent. Secondly, its introduction is being staged quite slowly."

Cars will be able to exceed the RDE test by 110% for NOx emissions and still be compliant. That 110% comes down to 50% in 2020 but it still gives manufacturers a healthy margin for error. Tests currently conducted by Molden and his team show that the average Euro6 diesel pollutes 400mg/km when the limit is set at 80mg - so five times above the limit. The cleanest engines are well below this limit, though, while the worst tested in the past year was 18 times above the NOx limit.

"Euro6 tells people that the engine is low-emitting but, actually, it covers a multitude of sins as some engines are still well over the limit, so people won't know if they really have a clean engine or not. It doesn't help consumers at all and a big reason we launched the EQUA Index is that it shows within Euro6 which engines are clean and which are the dirty ones," Molden continues.  

The on-road testing by Emissions Analytics takes four hours and covers a mixture of city, urban and motorway driving over 140 miles. The same weight is added to each vehicle - 250kg in total - which includes the driver and machinery that records the data, and air-con is set at a standardised level, with the car's default driving mode used throughout the test.

  If a car gets an A rating on the firm's EQUA Index, it meets the official NOx limit, even in real-world driving conditions. The firm also posts its average mpg figure produced in the test. The average gap Molden and his team have found between official and real-world tests is currently 30%, with diesel being slightly worse than petrol cars.

The data shows the biggest culprits are the smaller engines - especially when fitted to larger cars - and particularly diesels, which, according to Molden, only exist to perform well for the NEDC cycle, so we should start to see smaller 1.4-litre diesels disappear from line-ups as the new WLTP and RDE test are introduced.

Driving style

Drivers often get blamed for why the official figures and actual mpg results are so varied, and driving style does have an impact but, according to Molden, not as much as people may think. "The evidence we see is that the driver can have a moderate effect; certainly, driving more smoothly and anticipating the road ahead will have an impact, but there are other techniques like shifting up gears that make relatively little difference. These cars are really well optimised; there's only so much a driver can actually do to affect the fuel economy," Molden says.

Once again, smaller engines will be impacted more by driving behaviour as they are usually put under more strain if the driver wants to gain speeds quickly, but, as Molden explains, "driver behaviour is not the cause of our urban air problems and it's not the reason why real-world mpg is worse than the official figures. Drivers are not to blame; the dominant factor is how the official test has been gamed."

What about tax?

In the short term, taxation will continue to be based on the CO2 figures generated from the current NEDC test. However, fleets should expect this to change in the future as the WLTP becomes more established. We currently have the benefit-in-kind (BIK) tax rates set until 2019/20 and there's a strong feeling in the industry that it may see a significant overhaul at this point. The British Vehicle Rental and Leasing Association (BVRLA) and Association of Car Fleet Operators (ACFO) have made calls to the government to reform current BIK ratings with 'greater granularity' needed on low-CO2 vehicles to help incentivise uptake.
Nothing has been formally announced but Molden believes that, in 2019, there will be a hard switch over from NEDC-based tax to the new WLTP.

"I assume they'll just try to recalibrate it, though, instead of trying to get more tax from people," Molden continues. "The government is losing billions now on VED because cars have essentially become more efficient, so something will need to change."

What can fleets do?

Essentially, the new official WLTP will enable fleets to better benchmark cars against one another, and also gain a greater understanding of the emissions and fuel economy they will produce. Fleets can also prepare for possible tax changes by using the data available from Emissions Analytics or the official RDE figures once the test is in place, and only pick cars that fit within certain parameters for real-world NOx and CO2 emissions, and fuel economy. Emissions Analytics is currently working with Transport for London, using its data to review the current fleet, and help shape choice lists and vehicle requirements.

"It's perfectly viable that a fleet could be all EQUA A-rated within a three-year period, and there are enough A-rated cars on the market now, so you do have some selection," Molden explains. "The information exists; if fleets and leasing companies start constraining lists to reflect real-world NOx emissions, then that could have a far greater impact than initiatives such as clean-air zones.

"At the moment, there's been a widespread loss of confidence in the figures from manufacturers and a growing realisation that, with our figures, there is an alternative. The new official tests will squeeze out the worst performers in the market for NOx because they won't be able to get away with it anymore, but there's such a long road ahead for credibility of these figures to be rebuilt."