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The aim of this paper is to describe the development and the applications of a mathematical model for the vehicle driveline used to analyze the link between the performances car and vehicle driveability. It's well known that the car driveability depends by the dynamic response of the driveline car, whereas the classic performances depend by the coupling between engine's steady characteristic (torque and power curves) and vehicle's proprieties (weight, rolling resistance, drag coefficient, etc.) carried out by tuning of suitable gear shift ratios. The definition of the link between the driveability and the performances represents a very hard problem because it exceeds the limits in the field of the subjective perception, where the two aspects are themselves overlapped. To describe in analytical way this problem it's been introduced a new metric, where it's possible to evaluate at the same time the vehicle driveability and car performances.

The aim of this paper (which is the continuation of the work presented at the ISATA 2000 International Conference [1]) is to analyse the low frequency driveline torsional vibrations in a vehicle. It is known from many studies and investigations, that the driveline torsional vibrations are mainly responsible of the driver's performance perception and the vehicle's driveability [2, 3, 4]. So many manufacturers use the driveline's response in order to provide their vehicles with characteristics that are specific for the vehicle's segment class and the market. In this regard the vibration's behaviour has been investigated, studying some typical steady and transient vehicle manoeuvres. As a diagnostic guideline for the design's concept development, a driveline simulation model in Matlab/Simulink environment has been implemented. Therefore the basic features has been created to improve a complete vehicle co-simulation, using a engine cycle code and a mechanical driveline model.