French Prime Minister Manuel Valls has announced plans to reduce the use of diesel fuel in the country's fleet of vehicles.
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Last weekend the French PM (below) delivered a speech, in which he was quoted as saying: "In France, we have long favoured the diesel engine. This was a mistake, and we will progressively undo that, intelligently and pragmatically."

Next year, the government will introduce an identification and ranking system for vehicles, based on the amount of pollution they emit. This, according to the PM, will make it easier for local governments to limit access by and the use of highly polluting vehicles.

Although diesel engines are more fuel efficient and produce less carbon dioxide than their petrol cousins, they also emit greater quantities of nitrogen oxides (NOx). NOx gases react to produce low-level ozone, as well as smog and acid rain.

In March of this year, smog in Paris became so bad that officials were forced to ban half of the city's cars from driving, as well as offer free public transport.

Manual Valls by Flickr user fondapol

Another measure announced Valls will narrow the taxation gap between diesel and petrol fuels.

Currently the French government levies an excise of around 42.84 euro cents ($0.63) on every litre of diesel sold; the excise on regular unleaded petrol is substantially higher at about 60.69 euro cents ($0.89) per litre.

Under the government's plan, the excise, dubbed TICPE (taxe intérieure de consommation sur les produits énergétiques or domestic consumption tax on energy products), for diesel fuel will be raised by two euro cents ($0.03) per litre. It's expected that this increase will add 807 million euros ($1.2 billion) to the French treasury over the course of 2015.

Reuters claims that around 80 per cent of the vehicles on French roads use diesel motors.

The French government's latest move follows an initiative announced earlier this year by energy minister Segolene Royal, which granted cars buyers 10,000 euros ($14,700) if they switched from a diesel-powered vehicle to an electric one.