- The Real Driving Emissions test will be introduced from September this year
- It is designed to work alongside the new WLTP test cycle to produce real-world fuel economy and emissions figures
- Mercedes bosses said it will be an improvement but not an exact science
Rob Hull For Thisismoney.co.uk
Ever wonder why you can never achieve the fuel economy figures quoted for the car you drive?
It might say it will do 50mpg on the manufacturer’s website, but in reality it’s closer to 30mpg when you’re at the wheel.
It’s because the fuel economy and emissions tests for cars do not represent real-world driving conditions, which is why tests will be replaced this year with a more relevant version – but even that won’t give an accurate account of how efficient your car will be, warn Mercedes-Benz bosses.
Not not representative: Mercedes bosses have warned that the new fuel economy and emissions test for cars still won’t produce figures drivers will be able to achieve on the road
The WLTP/RDE (World Harmonised Light Vehicle Testing Procedure/Real Driving Emissions) test will become the new standard for car manufacturers from September.
It’s the second phase to move away from an old test that had been in existence since 1970 and had its last major update some 20 years ago.
But while it is expected to be a significant improvement on the outgoing measurements, Mercedes says it won’t produce like-for-like figures that drivers will be able to achieve day in day out.
When asked about the WLTP/RDE cycle by motoring title Auto Express, Mercedes’ head of certification of Emissions and Consumption Dr Christoph Höhmann, said: ‘It’s better than the old one. But if the expectation is that everything will be fixed, then in that respect it’s not right.’
The test will be split between a laboratory and a short cycle conducted out on real roads.
The lab test – the WLTP part – has been mandatory since September 2017, but the RDE addition will only become required from the same month this year.
However, there appears to be plenty of loopholes that can be used to manipulate the figures as there is a lack of direction in the protocol.
‘The framework [for RDE] does not say when you have to shift gears or whether you should be using items like the air conditioning or heated rear screen during the test,’ Dr Höhmann told Auto Express.
‘The air con could have a huge effect, but you don’t have to turn it on [in the test] and you will probably have it on in the real world.’
The Real Driving Emissions (RDE) test will be introduced from September this year
The comments from the Mercedes expert will do little to console drivers, who have been fed false information about the running costs and how much pollutants are being emitted by their cars for years.
Only since the exposé of Volkswagen’s emissions cheating scandal in 2015 has more attention been aimed at how manufacturers produce their fuel economy and emissions claims, forcing through the decision to switch test cycles this year.
However, experts have already warned that the miles per gallon and CO2 emissions figures still won’t be a representative example of what drivers should expect.
Here’s how the old test (NEDC) compares to the new WLTP measurement introduced last September. The test will be updated with the RDE portion of the test, taking real-world emissions measurements from all vehicles tested as of September 2018
Greg Archer, director of clean vehicles at campaigning company Transport and Environment – which has been pushing for test protocol for vehicles to be improved for years – said: ’The introduction of the WLTP and RDE tests marks an important milestone in the battle to ensure cars comply with environmental limits on the road and to end the cheating that has become endemic in emissions testing.
‘But new tests are not a panacea and will need to be further refined to ensure they are really representative of how cars are driven.
‘The forthcoming decisions on how and who approves cars for sale will be key to ensuring the system of approvals is independent and rigorously enforced.’
He concluded: ’The new tests will only help clean up our toxic air and tackle climate change if there are new, tighter emissions standards.
‘The EU is moving in the right direction but much still must be done to bring an end to dirty diesels and gasoline-guzzling cars.’