VW woes continue as accused of manipulating tyre systems

November 08, 2016

Volkswagen has been found once again to be manipulating official tests, this time at the expense of safety. Adjustments to the indirect tyre pressure monitoring systems (the TPMS) – used to prevent tyre blowouts – mean that they work in the laboratory, but would fail on the road.

Fiat has also been caught out by the new on-road test, research commissioned by environmental group Transport & Environment (T&E) claims. The group accuses Fiat and Volkswagen of penny-pinching on their cars at the expense of people’s safety.  

The TPMS is designed to alert the driver when the tyre reaches dangerously low pressure or is deflating, preventing dangerous blowouts. Two vehicles tested – a Volkswagen Golf and a Fiat 500L – failed to pass all or nearly all of the 16 real-world tests diverging from official EU ‘laboratory condition’ regulations. In the tests carried out by specialists Idiada, the Golf failed 14 and the Fiat did not pass any.  

The most suspicious results came when the laboratory test was repeated on tyres with some wear - the TPMS failed to warn of low tyre pressure. This indicates that the indirect systems were primed to get through official tests but become less sensitive once they were used on the road. Carmakers may be optimising indirect systems to be less sensitive after the initial test as their detection is based on wheel vibrations and rotations, which could be falsely triggered in various real-world conditions such as on varying road surfaces and in different temperatures – a false positive that would unnecessarily irritate the driver.  

Julia Poliscanova, clean vehicles manager at T&E, said: With Dieselgate, carmakers were caught willfully putting the public’s health at risk from poisonous emissions. Now we find manufacturers could be deploying similar defeat devices to get ineffective tyre pressure monitoring systems to pass safety tests […]. Investigations of the suspicious TPMS performance must be carried out. Our tests clearly show that the unsafe indirect systems put drivers, pedestrians and cyclists at greater risk of dangerous blow-outs.’  

Volkswagen and Fiat use ‘indirect’ TMPS technology which relies on tyre vibration and wheel rotations to detect low pressure, rather than the far more effective direct TPMS. This has dedicated sensors which accurately measure the pressure in each wheel – at a cost of only €10 more.  

This is – like Dieselgate – yet another area where the US is ahead of the game. While use of indirect TPMS is growing in Europe, the technology is used much less often in the US where vehicles are tested regularly over their lifetime. Currently, EU law mandates TPMS but does not differentiate between direct and indirect systems. T&E advocates an amendment to the new General Safety Regulation (GSR) to allow only direct systems. The new GSR, set to be proposed by the end of this year, should also require more on-road testing of cars to check their safety performance.  

In a separate incident, US regulators have found software installed on Audi branded vehicles that lowered their carbon dioxide emissions if it detected they were being used under test conditions. While the result was similar, the device was different to the ones found on Volkswagen cars that triggered last year's emissions scandal.






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