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 new metric coordinates are parameters which can identify in synthetic way the trade off between the drive comfort and the performance requirements.
The analytical model developed has been validated by comparing before the predicted and the measured longitudinal vehicle acceleration (detail behavior) and after, the predicted and the measured metric point (global behavior).
Both results show a good agreement between predictions and tests.
It's been made, also, a sensitivity analysis, for the more relevant car driveline parameters to carry out trends. These latter could be used to support the design, in the car concept definition, or testing in diagnostic to explain some experimental results.
At last it's been analyzed the influence of the engine control strategies on the dynamic car response, which effects can be well described in the new metric.
Moreover this approach (the analytical model with the metric) could be used in the car concept definition, because it may tune the brand car characteristic with its market requirements.