Researchers in the United States have undertaken field evaluations of in-vehicle devices that monitor driver behaviours and fuel consumption. Studies that tested the use of in-vehicle monitoring in emergency medical services (EMS) reported substantial improvements in driver behaviour through in-vehicle monitoring systems that gave drivers real-time feedback.[33][34] The researchers reported that the technology demonstrated sustained cost savings in regards to vehicle maintenance and required minimal retraining of drivers.[34] Another study of EMS drivers reported similar results and recommended gradual implementation of in-vehicle monitoring, with attention to defusing potential concerns regarding a punitive approach to corrective action.[35]