Diesel emissions inquiries widen to Renault and Fiat

Reuters: European carmakers were drawn into a widening probe of diesel emissions testing on Friday, with French prosecutors examining Renault and British authorities seeking answers from Fiat Chrysler Automobiles NV.

Volkswagen’s VOW_p.DE admission that some of its diesel vehicles were fitted with software designed to hide their true level of emissions has highlighted that most cars spew out far higher levels of health-threatening nitrogen oxide (NOx) in everyday driving conditions than in laboratory tests.

Renault said it respected all laws concerning exhaust emissions, adding that its vehicles did not have software enabling them to cheat on emissions standards.

The French clampdown follows allegations by the US Environmental Protection Agency (EPA) on Thursday that Fiat Chrysler, like Volkswagen, was potentially using illegal software to hide excess diesel emissions.

No manufacturer other than VW has been found to have installed software designed solely for the purpose of circumventing emissions tests, but regulators in Britain and Germany say that carmakers have made extensive use of a “thermal window” which allows manufacturers to turn down pollution-control systems for the sake of protecting an engine.

German investigators said they had found that some carmakers defined the “thermal window” in such a way that exhaust treatment systems were switched off most of the time.

Switching off or throttling back emissions treatment systems in cold weather reduces the risk of condensation building up in catalytic converters, which may otherwise cause rust and reduce exhaust-filtering effectiveness in the long run.