The price of diesel in France has slipped below 1 euro a liter for the first time since 2009 — at the height of the financial crisis. The price drop crosses a symbolic barrier that is likely to complicate government efforts to encourage cleaner transportation.

According to figures published late Monday, the average nationwide price of a liter was .99 euros.

Many European consumers prefer diesel cars because they get better mileage and are cheaper to fuel and maintain. In France, the preference is even stronger because of decades-old tax breaks the government is reluctant to lift despite evidence of health risks linked to diesel pollution. Paris Mayor Anne Hidalgo says she wants to "eradicate diesel" by 2020, but French consumers may instead be drawn to the new low prices.