Permanently engaged, the innovative Vehicle Dynamic Control system is activated under extreme conditions when vehicle stability is at risk, helping the driver to control the car. As befits a true Alfa Romeo, however, VDC is a sporting system that does not interfere prematurely, allowing the full satisfaction of driver control to the limit of critical conditions.
The VDC system continuously monitors tyre grip in both longitudinal and lateral directions. If the car starts to slide, VDC cuts in to restore directional stability. It uses sensors to detect rotation of the car body about its vertical axis (yaw), lateral acceleration, and steering input. Comparing this data with computer generated parameters, the system establishes whether the car is cornering within its adhesion limits or if the front or rear wheels are about to lose grip.
To restore the required trajectory, VDC generates a yawing movement to counter that responsible for the vehicles’ instability by braking the appropriate wheel individually and reducing engine power via the throttle.
Exceptionally smooth brake modulation and engine power reduction are key attributes of a system designed by Alfa engineers to maintain outstanding performance and driving satisfaction throughout its operation.
ASR is an additional feature of the Alfa 159’s VDC system, designed to limit wheelspin in cases of low road surface grip. This sophisticated system works at any speed and prevents the driven wheels from spinning by adjusting torque according to the grip coefficient detected at the time of slip.
The system recognises loss of traction via the ABS sensors, and activates two different control systems to restore grip: In the case of both driven wheels spinning it reduces engine power via the throttle. If only one wheel spins, however, it is automatically braked; the resultant effect being similar to that of a self-locking differential.
ASR not only optimises vehicle safety in conditions of minimal or constantly varying degrees of grip, but also greatly reduces mechanical stress to the differential and gearbox through effective control of low speed take-off and traction.
The system is activated automatically whenever the engine is started, but may be deactivated via a switch on the centre console. A flashing warning light indicates ASR operation, whilst a second light illuminates to indicate system faults or irregularities. ASR deactivation is required when snow chains are fitted to allow for their effective use.
The new Alfa 159 Sportwagon further benefits from MSR, which cuts in when a gear is shifted down abruptly under conditions of low grip, restoring torque to the engine to prevent skidding as a result of wheel lock-up.
Also integral to VDC, the Hill Holder system helps drivers pull smoothly away from an upwards-facing hill start. Operating via the ESP longitudinal acceleration sensor when first gear is engaged and both clutch and brake pedals are pressed, the control unit maintains front calliper pressure for about 1.5 seconds after the brake pedal is released to eliminate the risk of rolling backwards and ensure a smooth pull away. Hill Holder does not operate when setting off downhill in first gear, but does so when reverse is engaged and the driver wishes to back uphill.
In all, these features make the Alfa 159 Sportwagon a benchmark for its segment in terms of safety – one that is now certified by the 5-star Euro NCAP rating awarded to the Alfa 159 saloon, which acknowledges that the car has passed the most difficult tests simulating all types of accident (head-on, side-on, overturning, rear impact and fire) taking into account the various speeds at which impact may occur, the different types of obstacles encountered, and the need to protect occupants who may have widely varying physical characteristics. The Alfa 159 Sportwagon was designed and built to embody uncompromising quality, a concept that guided the entire process of the car’s development – starting with the vast number of tests to which is was subjected – right down to the manufacturing process. For the Alfa 159 Sportwagon, quality also means class-leading dynamics, obtained by careful calibration of the sophisticated suspension system, and the outstanding torsional rigidity of the all-new platform and bodyshell.Published 7 June 2006