Engineering news
Vehicle emissions testing regimes, including the UK's own Vehicle Certification Agency, are coming under intense scrutiny after the world's largest car maker, Volkswagen, was exposed as cheating in US tests.
In the latest developments, the UK government said it is to launch an investigation with the “relevant authorities” to restore public confidence in the vehicle testing regime.
Louise Ellman, chair of the Transport Select Committee, said: “I am very concerned about the potential implications for vehicles in the UK. There are questions over whether the testing authorities commissioned by motor manufacturers are truly independent. Do the results found in test conditions truly reflect real life situations on the road? It should not take a crisis to make the authorities act.”
She added that both anecdotal reports and research showed that a growing gap between real world performance of vehicles and laboratory tests were partly due to the “increased exploitation of flexibilities in laboratory testing by vehicle manufacturers”.
Experts have told PE common practices used to “game” the tests include the use of tweaked prototype cars, modified to reduce weight and improve performance,
Tim Barlow, principal consultant at the Transport Research Laboratory, said that laboratory testing practices were outdated and offered room for optimisation: “For the NEDC [New European Driving Cycle], they have to set the vehicle up on the dyno, so they need to know the forces, which are worked out by doing a coast down test. They can improve aerodynamics by taping cracks, using advanced lubricants, disconnecting the alternator or using a test track in a hot country at a high altitude.
“It is a stylised test that doesn't represent real world driving, but it is being improved in the future. Tests are overseen by the VCA [Vehicle Certifications Agency], but it doesn't oversee every test.”
Jane Thomas, global sales manager at Emissions Analytics, which uses portable equipment fixed to a car's exhaust to measure emissions as it is driven, said: “A fixed cycle can be learnt. There is always going to be scope to game the system. Emissions testing needs to be independent and done on the road, which is more representative than a fixed cycle. Spot checks and random testing would be more effective.”
Millbrook Proving Grounds, Bedfordshire, has been performing vehicles emissions tests since 1969, and is equipped with extensive test laboratories and portable systems to measure emissions. The site tests vehicles for both the government and the automotive industry.
Phil Stones, head of vehicle emissions testing at Millbrook said, that such techniques would not happen during “type approval”. He said: “That's cheating. The car has to be the same as it will be in the production version. You have to test at standard tyre pressures. You can't disconnect things. To say that you have to say that a government agency is corrupt. At the point it goes to type approval, the testing has to be witnessed by a government agency, the VCA in the UK.
“We test according to the regulations determined by the European Commission and the member states. They decide if the test is appropriate. It is a benchmark test, like the energy efficiency mark for a washing machine. It's going to depend on how you use it as to the actual performance.”
Vehicle testing for “type approval” is performed by a number of laboratories and test sites throughout Europe to check vehicles meet EU and UN standards for factors such as safety, emissions and recyclability. “Type” approval tests a single vehicle that is representative of an entire fleet of the same type of car.
The procedure for emissions and performance testing takes place on dynomotors in laboratories, where vehicles are run through the New European Driving Cycle (NEDC) to simulate typical driving. The NEDC was initially devised in the mid-1970s and has only been updated twice, in the late 1980s and in the early 2000's, to account for motorway driving and idling in traffic, since then.
The NEDC is expected to be superseded by a new global standard called the World Light Vehicles Test Procedure in 2017, which aims to better represent real world driving conditions and practices.