The official NEDC fuel economy and emissions test runs for around 20 minutes.
This could indicate that Fiat is using software to pass official emissions tests without using expensive aftermarket exhaust filters. Authorities are now investigating, and are carrying out further tests on Fiat models.
Fiat has so far declined to comment.
German test body the Federal Motor Transport Authority (KPA) made the discovery during testing following the Volkswagen ‘defeat device’ scandal, although it added this system is not necessarily illegal.
Car manufacturers are allowed to alter emissions management systems to protect the engine from damage – it’s a so-called ‘thermal window’ that limits the operation of exhaust filters.
The use of such systems helps improve performance and extent service intervals, although it’s a practice that both regulators and environmental groups have criticised. Many are now calling for clarification at an European level on how such systems can be used.