BACKGROUND ART As is known, the high power and fast response of high-performance road sports cars make them fairly difficult to drive, especially in unfavourable weather.

To make normal driving safer, high-performance sports cars are therefore equipped with various electronic driver-aid devices, such as an ABS (Anti Block System, for preventing the wheels blocking when braking), ESP (Electronic Stability Program, for controlling vehicle stability), ASP (Anti Skid Program, for preventing skid of the drive wheels), and electronic suspension control (for adjusting suspension response to stress).

To enable the driver to adapt response of the electronic driver-aid devices to the desired driving mode and weather conditions, the passenger compartment of the

vehicle is normally equipped, on the central tunnel close to the gear lever, with a selection button for transmitting the driver-selected driving mode-normal or sport-to a central control unit.

The gradual increase in the number and complexity of electronic driver-aid devices calls for increased communication between the driver and the central control unit, to enable the central control unit to control the electronic driver-aid devices as best suited to both driving mode and weather conditions. Accordingly, it has been proposed to equip the central tunnel with a series of buttons enabling the driver to choose between various dynamic vehicle performance modes.

Tests have shown, however, that the above solution, featuring a number of buttons on the central tunnel, is complicated to use and tends to distract the driver when driving the vehicle.

DISCLOSURE OF INVENTION It is an object of the present invention to provide a vehicle which is cheap and easy to produce, and which, at the same time, provides for eliminating the aforementioned drawbacks.

According to the present invention, there is provided a vehicle as claimed in the attached Claims.

BRIEF DESCRIPTION OF THE DRAWINGS A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which:

Figure 1 shows a schematic plan view of a rear-drive vehicle in accordance with the present invention; Figure 2 shows a larger-scale front view of the steering wheel of the Figure 1 vehicle.

BEST MODE FOR CARRYING OUT THE INVENTION Number 1 in Figure 1 indicates a vehicle having two front wheels 2 and two rear drive wheels 3, and comprising a front internal combustion engine 4 producing a drive torque which is transmitted to rear drive wheels 3 by a power train 5. Power train 5 comprises a clutch 6 housed in a casing integral with engine 4 and for connecting the drive shaft of engine 4 to a propeller shaft 7 terminating in a mechanical power gearbox 8 at the rear; and a self-locking differential 9, with electronic lock percentage control, is cascade-connected to gearbox 8, and from which extend two axle shafts 10, each integral with a respective rear drive wheel 3.

Vehicle 1 also comprises a known electronically controlled braking system (not shown in detail) acting on wheels 2 and 3; and a known suspension system (not shown in detail) with electronically controlled suspension response. Vehicle 1 also comprises a passenger compartment 11 equipped with a steering wheel 12 for imparting a turning angle to front wheels 2.

Vehicle 1 comprises a central control unit 13 for supervising operation of the active components of vehicle 1, and connected to a number of sensors 14 distributed inside vehicle 1 to real-time detect respective

parameters of vehicle 1, such as the travelling speed of vehicle 1, the turning angle of vehicle 1, the yaw speed of vehicle 1, the lateral acceleration of vehicle 1, the longitudinal acceleration of vehicle 1, the rotation speed of each wheel 2 or 3, and the drive torque generated by engine 4. Central control unit 13 may obviously be defined by a number of physically separate processing units connected to one another, for example, by a data BUS; and, as opposed to a physical sensor 14, an estimation algorithm may be implemented by central control unit 13 to determine one or more parameters of vehicle 1.

Internally, central control unit 13 implements the functions of various electronic driver-aid devices, and in particular prevents blocking of wheels 2 and 3 when braking (so-called ABS function), prevents skidding of rear drive wheels 3 (so-called ASP function), controls the stability of vehicle 1 (so-called ESP function), and provides for electronically controlling suspension response, servocontrol of gearbox 8, and the lock percentage of self-locking differential 9. Central control unit 13 also modifies the operating parameters of the active components of vehicle 1 (typically engine 4 and the above electronic driver-aid devices) to modify dynamic performance of vehicle 1. To enable the driver to choose the dynamic performance of vehicle 1, a selection device 15 is provided inside passenger compartment 11 of vehicle 1, and is operated by the driver to transmit the

selected dynamic performance of vehicle 1 to central control unit 13.

As shown in Figure 2, selection device 15 comprises a switch 16 fitted to steering wheel 12 and which is rotated about a respective axis 17 between four positions (indicated A-D for simplicity), each corresponding to a respective dynamic performance of vehicle 1. Steering wheel 12 has a recessed seat 18 housing switch 16, and a cover 19 hinged to steering wheel 12 and for closing seat 18.

When switch 16 is set to position A (so-called"ICE" position), central control unit 13 sets the dynamic performance of vehicle 1 to drive on low-grip road surfaces. More specifically, in position Ar the performance of engine 4, servocontrol of gearbox 8, and electronic control of the lock percentage of self-locking differential 9 are set for low-grip operation, and electronic suspension response control and electronic control of the stability of vehicle 1 are set for normal operation.

When switch 16 is set to position B (so-called "SPORT WET"position), central control unit 13 sets the dynamic performance of vehicle 1 to drive on low-grip road surfaces in sport mode. More specifically, in position B, the performance of engine 4, electronic suspension response control, and electronic control of the lock percentage of differential 9 are set for normal operation, and servocontrol of gearbox 8 and electronic

control of the stability of vehicle 1 are set for sport operation.

When switch 16 is set to position C (so-called "SPORT DRY"position), central control unit 13 sets the dynamic performance of vehicle 1 to drive on firm-grip road surfaces in sport mode. More specifically, in position C, the performance of engine 4, electronic suspension response control, electronic lock percentage control, servocontrol of gearbox 8, and electronic control of the stability of vehicle 1 are set for sport operation.

When switch 16 is set to position D (so-called "NORMAL"position), central control unit 13 sets the dynamic performance of vehicle 1 to drive in safe conditions in touring mode. More specifically, in position D, the performance of engine 4, electronic suspension response control, electronic lock percentage control, servocontrol of gearbox 8, and electronic control of the stability of vehicle 1 are set for normal operation.

Switch 16 may also be set to a position E, in which the dynamic performance of vehicle 1 is set to track racing mode. When switch 16 is set to position E (so- called"RACE"position), some of the electronic driver- aid devices (typically ESP, ABS and ASR) are preferably disabled to permit full driver control of vehicle 1.

Switch 16 can only be set to position E from position C, by moving it linearly, in a direction crosswise to the

axis 17 of rotation of switch 16, into a control position, from which switch 16 returns automatically to position C, normally by means of an elastic element (not shown in detail). The dynamic performance of vehicle 1 is set according to the angular position of switch 16, once engine 4 of vehicle 1 is turned off. This is indispensable for ensuring the driver does not inadvertently leave switch 16 in position E, and therefore some of the electronic driver-aid devices disabled, and for ensuring track racing dynamic performance of vehicle 1 is not maintained whenever engine 4 is started up again.

In an alternative embodiment, switch 16 is mounted to slide along its axis 17 in opposition to a further elastic element (not shown in detail), and is pressed by the driver to command performance by central control unit 13 of a racing-start procedure, if vehicle 1 is stationary when switch 16 is pressed. The racing-start procedure is used to pull away with the maximum possible acceleration compatible with the selected dynamic performance of vehicle 1. More specifically, the racing- start procedure is only performed if switch 16 is in position B or C when pressed; or switch 16 can only be pressed when in position B or C.

Road tests have shown selection device 15 as described above to be highly ergonomic, and easy to operate by both skilled and occasional drivers.