Leading French automobile manufacturer PSA Peugeot Citroen published Tuesday "real-world" fuel consumption figures for three of its diesel cars, seeking to win over wary customers after the Volkswagen pollution cheating scandal.

Peugeot Citroen said the initiative was a world first, launched in the aftermath of German rival Volkswagen's admission last year that it had fitted 11 million diesel engines worldwide with devices that fool official pollution tests.

"We were obviously shocked by what happened with Volkswagen-gate and in some way, like the profession, the whole automobile industry, we were affected by the situation and deeply upset," Carlos Tavares, chairman of the group's managing board, said on the sidelines of the Geneva International Motor Show.

"It was important to safeguard our customers' trust in relation to knowing their automobiles' consumption," he told a conference.

The French car maker said the results were based on tests designed by two environmental groups, Transport & Environment and France Nature Environment.

The cars were driven on public roads in town, outside town and on motorways near Paris in "real-life" driving conditions with passengers, luggage, roads with hills and the air conditioning switched on, Peugeot Citroen said in a statement.

"Peugeot Citroen is the first car maker to adopt such an approach," the company said.

Peugeot Citroen promised to reveal the real-world fuel consumption results for 30 models "before summer 2016".

- 'Learn from past mistakes' -

As expected, all the "real-world" fuel consumption figures exceeded the results of the existing official laboratory-style New European Driving Cycle (NEDC) tests, which were thrown into question by the Volkswagen scandal.

The "real world" tests showed:

- A medium-sized sedan Peugeot 308 consumed 5.0 litres for 100 kilometres, compared to just 3.2 litres in the NEDC tests;

- A Citroen C4 Picasso people carrier drank 5.6 litres for 100 km, compared to 4.0 litres in the NEDC tests;

- And the premium subcompact DS 3 used 4.9 litres over 100 km, compared to 3.6 litres in the NEDC tests.

All three cars were equipped with 1.6-litre, 120-horsepower engines with manual gearboxes.

New official tests called the Worldwide Harmonized Light Vehicles Test Procedures, aimed at better measuring real-world fuel or energy consumption and pollution emissions are being defined for introduction in 2017.

For now, the official NEDC tests are the only recognised thermometer for car performance in Europe, said Gilles Le Borgne, head of research and development at Peugeot Citroen.

"If others want to join our initiative we would be delighted," he said, adding however that no other manufacturer had shown interest in doing so.

Peugeot Citroen first announced the real-world testing initiative in November last year, two months after the Volkswagen cheating scandal broke.

Volkswagen admitted the existence of the illegal cheat software on diesel engines which limits the output of toxic nitrogen oxides during emissions tests by regulators.

But when the vehicles are in actual use, the software allows them to spew poisonous gases far above permitted levels.

Volkswagen chief Matthias Mueller called in Geneva on Monday for his company to "learn from past mistakes".

In 2015, VW's own-brand sales fell five percent to 5.82 million vehicles worldwide, the first decline in 11 years, the company has revealed. On top of lost earnings, VW is facing a barrage of legal complaints related to the scandal.

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