tract: In this paper we show a complete process for unsupervised anomaly detection for the average fuel consumption of fleet vehicles that is able to explain what variables are affecting the consumption in terms of feature relevance. For doing that, we combine the anomaly detection with a surrogate model that is able to provide that feature relevance. For this part, we evaluate both whitebox models from the literature, as well as novel variations over them, and blackbox models combined with local posthoc feature relevance techniques. The evaluation is done using real IoT data belonging to Telefónica, and is measured both in terms of model performance, as well as using Explainable AI metrics that compare the explanations generated in terms representativeness, fidelity, stability and contrastiveness. The explanations generate counterfactual recommendations that show what could have been done to reduce the average fuel consumption of a vehicle and turn it into an inlier. The procedure is combined with domain knowledge expressed in business rules, and is able to adequate the type of explanations depending on the target user profile.