Tests by the Federal Motor Transport Authority found that the exhaust emissions treatment switches off after 90 minutes.

German authorities have reportedly uncovered an alleged emissions 'defeat' device in the Fiat 500X.

Tests performed by the Federal Motor Transport Authority (KBA) found that emissions control treatments switched off after 90 minutes, according to a Spiegel report.

The KBA is said to have previously found an alleged defeat device that disabled emissions systems after 22 minutes -- suspiciously close to the 20-minute lab test cycle. Fiat allegedly claimed to have removed the questionable algorithm amid pressure from the EU, but follow-up tests by the KBA continue to show suspicious behavior.

In an official statement, Fiat declined to comment on "internal documents of German authorities." The company claims the Italian authorities have already "checked and re-confirmed" emissions compliance for the 500X.

Curiously, a 90-minute shutoff would appear to have little benefit for drivers or the automaker. Such a system would only engage during rare long-haul trips, as most Europeans spend less than an hour driving to or from work every day.