Ile-de-France was the most expensive region on average, at €682 per vehicle per year, a full €150 more on average per year than the cost in Brittany, updated figures have shown.
Overall, the Provence-Alpes-Côte d'Azur region is the second-most expensive area (€656); followed by Auvergne-Rhône-Alpes (€616), and Grand Est (€594).
Every region has seen an increase of at least 1.2% this year, if not more. Hauts-de-France, for example, saw a jump of 4.4%, to an average cost of €615, while Occitanie rose by 3.3%, to an average cost of €565.
The difference - and the overall rise - across the country is due to several factors.
Accident rates have been rising in departments such as Finistère, Somme and the Nord, meaning that average insurance costs there have respectively risen by as much as 4.8%, 5.4%, and 7.5%.
Bad weather can also cause rates to rise, with storms and extreme weather in Brittany and Haut-de-France in 2017 having a knock-on effect on insurance prices in 2018.
A rise in payments paid out to claimants can also cause a jump in prices for everyone, with 2017 seeing a 2% increase.
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