Currently reading: New WLTP emissions test: when it's in force and how it could affect your car
Overhauled economy and emissions tests are set to make their mark this autumn as car makers get to grips with tough new regulations
Jim Holder
3 mins read
17 April 2018

Over the next few months, you could drive home one night, park up and then get in your car the next morning only to find that it's 20% less fuel efficient and 20% more polluting than when you last turned the key.

How so? Well, the car you had yesterday will obviously still be the same as it is today, but its official – on paper – efficiency and environmental ratings will be certified to a new, tougher standard, called the Worldwide Harmonised Light Vehicle Test Procedure (WLTP), with nitrogen oxides (NOx) and particulate figures verified by the Real Driving Emissions (RDE) test which, as its name suggests, will be conducted on real roads.

That the tests are complex is not in doubt: engineers at Mercedes-Benz estimate they take twice as long as the previous – and now discredited – New European Driving Cycle (NEDC) test, and that the legislative requirements, including paperwork, are currently “turning jobs that took weeks into ones that take months”.

How will car makers meet new CO2 laws?

Discussions about the new regulations began in November 2007 at the United Nations Economic Commission for Europe (UNECE), when concerns at the mismatch between NEDC and achievable real-world figures first hit the headlines. That the new regulations arrive so soon after the Volkswagen-instigated Dieselgate affair is mostly coincidence, but their implementation sped up and industry opposition faded quickly in the face of the scandal.

Mike Hawes, chairman of the Society of Motor Manufacturers & Traders (SMMT), said: “This is an opportunity to reassure consumers that their cars will achieve figures much closer to the official ones.”

The standards are being phased in over time and should start to hit the mainstream from this autumn, when the results will have to be formally declared. Testing has already begun, with authorities using the interim period to work out an accurate conversion between new and old measurement systems so that fair comparisons can be drawn. The German Association of the Automotive Industry (VDA) estimates that, on average, fuel economy and CO2 figures will increase by 22%.


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BMW is among the latest manufacturers to have released new WLTP figures for its line-up. CO2 outputs of cars in its range increased by as much as 14%. Late last year, Volkswagen revealed that its new Up GTI had experienced a 15% growth in CO2 output when its WLTP results were compared with NEDC ones.

New UK diesel tax hike now in force

The tests are ramping up towards full implementation from the start of 2021, when the permitted difference between the lab-based WLTP test and the open-road RDE test will be greatly reduced. At present, the accuracy of the test equipment for real-world measurements means a significant margin of difference is allowable.

With the new regulations in full swing, Europe will be able to credibly claim that it has the toughest emissions regulations in the world, and the industry’s reputation, shot down by the Volkswagen scandal, should be, in part, restored. Why in part? Despite its name, the WLTP is only being adopted in full by the European Union, Great Britain, Norway, Iceland, Switzerland, Liechtenstein, Turkey and Israel.

Other countries are adopting elements of the regulations, notably around diesel and in China, while others, including the US and Brazil, are going their own way. It may only be those with long memories that remember by then, but it was due to different regulations being applied in different countries that tempted Volkswagen into its crime in the first place.

Read more

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BMW M3 F80 to be axed in August due to new emissions test

Join the debate


17 April 2018

 Drivers worked this out years ago, maybe not the emissions but defo the over optimistic mpg figure given by the maker.........

17 April 2018

So it seems that the Worldwide Harmonised Light Vehicle Test Procedure is anything but worldwide, and manufacturers must continue to optimise and test their vehicles to different standards operating in different parts of the world. How daft is that given the massive cost and effort involved and given that their products will all be driven on the same planet? 

The authorities might just as well have carried on with the NEDC test with a +20% fiddle factor to bring the figures roughly in line with the new test, with pollutant emissions verified by the RDE on road testing. One of the problems with both standard tests is that they do not involve brisk driving using full throttle and high engine revs (where pollutants are likely to be worst). So manufacturers will continue to optimise cars to pass the test, ignoring what happens when drivers use a car's full performance, drive badly or skimp on car maintenance. 

Still, at least the new regime will keep the testing experts in gainful employment and raise a little more tax revenue for our government... 

17 April 2018
According to ADAC ecotests, the hybrids that Toyota has long sold globally score well in both the lab WLTP and on-road driving. If you design for real low-emissions from the outset, instead of designing to the test, you will not incur additional costs when the test gets more realistic.

17 April 2018

The press make more of these figures than anyone. No system is perfect, just knock off 25-30% and be done with it!

17 April 2018

Our experience with VW Audi is 40% take off for diesel 64mpg in the golf is more like 38mpg and for the tsi 1.4 petrol i take of about 35% so 60mpg becomes 38 to 40mpg.

17 April 2018

...VW, AUDI, SEAT, SKODA telling the mother of all motoring lies and so like children that cannot be trusted (that's governments as well as car manufacturers) we have this...and I'm glad. 

17 April 2018
That's being too kind. More like double that in case of most European built cars that optimised cheating to a whole new level. Funny to read Hawes' comment. As if he cares about the efficiency, fair play or environment. BTW these brand spanking new tests have built-in special allowance to let dirty diesel pose as "clean". You wouldn't hear Hawes babbling about this discrepancy.

17 April 2018

Not sure about the rest of Europe but back here in the UK, we were provided with three economy figures:

urban driving, 56mph and 75mph.

Those EU tests were then introduced which provided a combined figure, the result of which those who drove in urban environments expected to achieve, those who drove at high motorway speeds also expected to achieve as did those Sunday afternoon drivers.

Have to say that under the original system, the figure for 75mph proved to be a far more  accurate an average than the combined does today.

Co2? Nox? g/km?  Lets face it, only tree huggers are concerned with these figures, the only impact for the remaining 99% of us is how much tax will it attracts.

110g/km or 131g/km? When you pass an airport and see a Jumbo take off, or pass a port and see an oil tanker depart, or trains coming out of Waterloo, or even that bus with three passengers on it, or as you pass Eddie Stobbart on the motorway, the difference in your car's Co2 or Nox doesn't make one iota of difference. It's there as a revenue generator.

17 April 2018

 when we are all driving a fully autonomous EV of whatever type, what will the pollution be like then?, I’m talking from Cars to planes and trains any thing powered by fossil fuels, can’t count ships because I don’t think we’ll ever see an EV Tanker, but everything else is possible, we all have different drivin* styles, we all drive differently depending what mood we’re in, there are countless variables so quoted mpg is at best an approximation, only when we are not in control of the Vehicle as in full autonomous roll will the vehicle possibly do the quoted mpg.....

17 April 2018
All this extra testing and cost is because the manufacturers didn't play straight. The difference between NEDC and real world emissions/ fuel consumption has little to do with the test cycle and lots to do with cheating.

They use cheat devices to turn off emissions control during the lab tests. They also used various other dodgy measures to make sure that the "road load" used on the static tests were much less that the actual load during driving.

There is nothing fundementaly wrong with the NEDC. It's all down to cheating and now the motorist is picking up the tab for manufacturers deceptions.


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