Instantaneous consumption models are designed to provide an accurate description of fuel consumption by relating the instantaneous rate of consumption with the vehicle acceleration, speed and the engine dynamics. In principle, instantaneous consumption models allow users to calculate the fuel consumption for any profile of vehicle operation. Some kind of models that take into account only driving dynamics can be used to describe the variability of consumption. The procedure used by this type of models is to establish reference matrices (related to specific time intervals) that for each combination of speed and acceleration determine the rate of fuel consumption. This paper Describes the design of a mobile application for the estimation of consumption, and user behavior, that applies models of instantaneous consumption. A preliminary experimental survey has been the carried out to obtain a large data base related to the acquisition of cinematic and engine parameters to allow the development of the mobile application. The experimental acquisition of parameters was accomplished in dynamic driving, connecting the OBDII port to different models of vehicles. With this procedure, reference matrices of fuel consumption for each specific class of emission (as required by ECE 15.03 - Directive 78/665/EEC and ECE 15.04 - Directive 83/351/EEC) have been obtained. The mobile phone application, after receiving as input the vehicle specifications provided by the user, can associate the specified matrix of consumption to the cinematic parameters (instant speed and acceleration obtained by GPS measures) and by using each pair of speed and acceleration can give an estimate of consumption values. At the end of the trip the user can take view of all device information on consumption also by geo-displaying the information on a map (showing the path and the related point by point consumptions). The output of the system, that can also provide information related to the dynamic behaviour and energy management in the user guide style, have been confronted with real consumption data. The advantage of the application is to estimate fuel consumption and driving style, from just GPS data, without connecting the phone to OBDII port.