The environment ministry invoked a “safeguard clause” in reiterating on 28 July the ban, which began in June.
Legally, the French government had the right to do so as the new class A, B and CLA series did not conform to European environmental regulation on coolants in car air-conditioning systems.
A 2007 EU automotive directive has a safeguard clause allowing member states to block the registration of vehicles which could pose a serious risk to road safety, the environment or public health.
The European Commission said it was unacceptable and against the spirit of the directive for Daimler, the parent of Mercedes, to change its coolant and may launch infringement proceedings against the group.
The French decision comes not long after German car manufacturers forced the hand of the European Council of Ministers to push back the signing of stringent 2020 carbon dioxide emissions targets.
“French cars emit less CO2 and would have been favoured by a hardening of the climate rules. The issue with air-conditioning has a direct answer: If you water down future standards, respect at least current standards,” said an industry source.
Since 1 January 2013, the Commission has obliged car-makers to use more environmentally-friendly coolants in new car models. Most recent Mercedes, constructed by German multinational Daimler, use R134a, a gas coolant with strong greenhouse gas effects. It is 1,400 times more toxic than CO2.
According to the EU directive, coolants cannot go beyond a greenhouse gas effect of more than 150 times that of CO2. An example is R1234yf, a replacement gas produced by US chemical giant Dupont. Its climate impact is just four times that of CO2.
R134a remains the main coolant used in Europe, France included. The KBA, Germany’s motor transport authority, allowed the continued use of the gas under the pretext that its replacement could be flammable. Laboratory tests had shown that R1234yf could catch fire under certain conditions.
But after years rigorous testing by manufacturers, the Commission declared that such fears were unfounded. The KBA and Mercedes will have to present new evidence before 20 August to explain their position.
Meanwhile, other European manufacturers do not intend to find other solutions. The theory that CO2 could be used as a coolant “is not necessarily a winner in terms of CO2 emissions, if the lifecycle of the vehicle is taken into account”, said a spokesman for Renault.
The French auto manufacturer has released no new models since the start of the year. The Germans have labelled as dangerous Renault's Zoe electric car, equipped with the new coolant.
ACEA, the main car manufacturers lobby group in Brussels, has declined to be drawn on the touchy subject. “We do not have an overarching position from European industry on coolants,” a spokesperson said.
The Commission’s industry directorate says that the issue should leave no manufacturer with a competitive advantage in the market. In France, it is the Mercedes distributors who protest the loudest.
Jean-Claude Bernard, the president of the distributors association, says the registration ban could have affected as many as 5,000 sales. The re-seller has written a letter to the environment ministry highlighting the threat of redundancies.
The debate remains theoretical, according to a distributor in the west of France who continues to sell Mercedes. Despite the debate between Paris and Brussels, French local administrations have not stopped registering Mercedes. “It is still a bad commercial hit for German cars,” the distributor said.