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The term driveability describes the driver's complex subjective perception of the interactions with the vehicle. One of them is associated to longitudinal acceleration aspects. A relevant contribution to the driveability optimization process is, nowadays, realized by means of track tests during which a considerable amount of driveline parameters are tuned in order to obtain a good compromise of longitudinal acceleration response. Unfortunately, this process is carried out at a development stage when a design iteration becomes too expensive. In addition, the actual trend of downsizing and supercharging the engines leads to higher vibrations that are transmitted to the vehicle. A large effort is therefore dedicated to develop, test and implement ignition strategies addressed to minimize the torque irregularities. Such strategies could penalize the engine maximum performance, efficiency and emissions. The introduction of the dual mass flywheel is beneficial to this end.

In the development process of actual cars it is more and more important to be able to evaluate in a detailed and fast way the impact, on the fuel consumption, of components and management strategies of the auxiliary systems. For these reasons, there is the need to develop and test specific tools. One of the most consuming subsystem is the Air Conditioning system: to be able to integrate it in a dynamic simulation model is going to be of outmost importance in the near future, since it is most likely that in some countries (see incoming California legislation) vehicle fuel consumption will be measured with the A/C system “ON”. FIAT Auto and Centro Ricerche FIAT have jointly developed a simulation tool, DrivEM, that integrates three dedicated simulation models: Drivetrain© for vehicle performance & fuel consumption, SACS for air conditioning systems and BILELCO for electrical system analysis.

The increase of the electrical power required by current vehicles suggests the need to evaluate its impact on fuel consumption, emissions and performances. Moreover, due to the growing amount of cars equipped with Air Conditioning System, a deep knowledge on how these additional loads influence vehicle performances is required. Often, the mechanical power requested by electrical and AC systems is comparable to the mechanical power necessary to move the vehicle (or sometimes even higher) and this happens mainly during urban driving cycles. Drivetrain 3.0 is an integrated simulation model for vehicle energetic evaluation and management; fuel consumption and performances on a generic speed vs time driving cycle are dynamically evaluated as a function of electrical power loads and their possible management strategies. Other additional mechanical loads (i.e. climate compressor) and the related transmission efficiency could also be taken into account.