“We are working on it,” said spokeswoman Lucia Caudet at the commission's last daily press conference of the year.

“You will see some developments there shortly. Not over Christmas though.”

Following the Dieselgate scandal, which involved Volkswagen Group equipping cars with defeat devices, Germany and the UK found that many carmakers are using such defeat devices in diesel cars.

These devices switch off, or turn down, the anti-pollution technology under certain circumstances.

Under EU law, that is allowed when it is required to protect the engine. However, during “normal use” of the car, defeat devices are banned.

Some cars use defeat devices under conditions that many consider normal: like when it is 17C or colder outside.

But Germany concluded in April that EU law, which it initially agreed to, was too vague to determine if a defeat device is legal or not.

The commission disagrees that the law is vague, but at the same time committed in June to provide national authorities legal guidance that helps them interpret the law and determine if a defeat device is allowed.

Last September, the responsible EU commissioner told MEPs that the guidance will be ready “by the end of the year”.

“The guidance will be tabled by December, hopefully the beginning of December,” she said.

Fiat: Germany vs Italy

Meanwhile, a suspicion of cheating is still hovering over Fiat.

According to the German car approval authority, Fiat had used an illegal defeat device in one of its models, which changed the anti-pollution system after 22 minutes. The official test is 20 minutes.

But the Italian authority, who had approved the model in question, said there was no defeat device. Fiat's parent company FCA is an Italian-American firm. Fiat denies doing anything illegal.

Because Italy approved the car, only Italy can take action.

In September, Germany asked the commission to mediate. According to spokeswoman Caudet the commission's “mediation mechanism” is “not a very muscled mechanism”.

She said on Thursday there was a first meeting with German and Italian representatives in November, and that a next meeting will be scheduled “shortly”.

Meanwhile, Fiat models with suspiciously high emissions are still driving around Europe, as are the millions of other cars with defeat devices.

JRC report

By e-mail later on Thursday, spokeswoman Caudet also gave an update about suspicious emissions results found by the EU's Joint Research Centre.

The measurements, done in August, had not yet been sent to national authorities for over four months. They have now, said Caudet, after being double-checked.

One of the measured results in an Audi car turned out to be lower than expected and thus less suspicious.

However, there were still several instances in which emission values shot up when the official test was changed only slightly. This may give the German car approval authority sufficient reason to ask Audi to give an explanation.