According to this article if you are caught driving in France without a reflective jacket and a warning triangle you could face a fine. The equipment which is not a legal requirement in the UK must be carried in the vehicle under French law. People who do not have it will have to pay a fine of between £70 and £110 whilst the cost of purchasing the kit can be as little as £29.99. The French authorities have been accused of specifically targeting UK registered cars because many UK drivers are unaware of the requirement. Under French law vehicles must have at least one reflective jacket for the driver although many French families carry a jecket for each member of the family.