The technological heart of the Cadillac Seville, now also available in Europe, is the advanced Northstar system. The V8 aluminum engine makes the Seville the most powerful front-wheel drive production car in the world. The Northstar system also ensures an extremely high level of active safety.
The Northstar system comprises the following:
- 4.6-liter V8 engine
- StabiliTrak - the most advanced stability control system
- CVRSS - Continuously Variable Road Sensing Suspension
- PAS - Performance Algorithm Shifting for "smart" transmission
- Magnasteer - speed-sensitive power steering assist
- MagneRide (MR)
The Northstar power pack is Cadillac's state-of-the-art aluminum 4600cc V8.
The engine is tuned to produce 224kW (305 hp) at 6000rpm.
with maximum torque of 400 Nm (295 lb. ft) generated at just 4400 rpm. Maximum speed is 240 kph, with 0-100 kph in 6.8 seconds.
Yet despite the awesome power output, Seville owners are easily able to reject any suggestion that their model may be wasteful of fuel. For 2001, fuel economy is reduced by 0.2 liters per 100 kms to reach a creditable 13.9l/100km. There is an improvement in emissions too, through the use of secondary air recirculation on start-up and a very fine fuel-spray injection system. Certified as EURO 3, Seville CO2 emissions have been reduced to 330g/km (was 337g/km). This figure would not disgrace a luxury sedan with a substantially smaller engine.
The engine is so reliable and refined that in normal operation its first major tune-up (changing plugs) is scheduled for 160,000 kms.
Sophisticated monitoring systems make use of 29 sensors across the powertrain and irregularities are instantaneously spotted and rectified.
Should the engine lose coolant, after a minor accident for example, Seville can limp home on four cylinders at speeds of 80kph giving the driver the chance to reach a safe location. The engine accomplishes this by alternately delivering fuel to four of the eight cylinders. The remaining four do not fire, but continue pump air which cools the engine.
The stunning performance from the most powerful front-wheel drive production car is linked to the ultra-advanced StabiliTrak 2.0 stability control system.
StabiliTrak sensors measure steering angle and other inputs from the driver to determine what he or she wants from the car. If the car is not responding appropriately a computer applies the correct individual front brake to help keep the car on the intended course. And in the unlikely event of Seville losing lateral traction at both front and rear axles, and facing the danger of a significant sideslip, both front brakes are applied momentarily to slow the car and allow it to regain stability and return to its true direction.
Continuous development of StabiliTrak has added active steering effort compensation, known by its initials of ASEC. In low-traction or emergency situations, the steering effort is temporarily raised as StabiliTrak commands the Magnasteer system to reduce the degree of power assistance.
There is more instant help in control in abnormal conditions through Seville's continuously variable road-sensing suspension (CVRSS). This delivers optimum body and wheel damping under virtually all driving conditions by independently adjusting the damper settings at each corner of the car and responding in real time. CVRSS matches damping required to the severity of the input, enabling a refinement level not previously achieved. The dampers vary from luxury sedan-smooth to racing car-firm in milliseconds.
For the driver and passengers this means markedly better rolling smoothness, road isolation and impact feel with exceptional control during a driving emergency.
Seville also utilises a Performance Algorithm Shifting programme that lets the gearbox perform intuitively like a manual during aggressive driving. PAS monitors the driver's use of the gas pedal, and cornering and braking, takes information from the car's many sensors like that provided in StabiliTrak. Without fuss, it takes its cue from the driver's actions and activates itself without further prompting. The automatic gearbox then performs like a manual box.
Example: In hard cornering, the "smart" transmission will hold its gear to avoid mid-corner upshifts that may upset the car's balance. As a driver brakes for a corner, the transmission changes down to the right gear for the cornering speed, just as a skilled driver would do with a manual box. It then holds the right gear through the acceleration out of the corner.
The Seville's Magnasteer variable-assist, speed-sensitive power rack and pinion steering system uses a variable magnetic field to increase or decrease steering effort as needed. This allows for a wider range of adjustability, and there are no steps or irregularities in the boost curves. Seville uses a straight 14.8:1 steering gear ratio rather than a variable ratio for the fastest response.
Magnasteer is also sensitive to lateral acceleration. When sensors determine the cornering rate is up, steering effort is automatically increased to enhance the driver's road feel.
The next generation of active suspension, utilizing MR technology, is a further example of innovation. Developed by Delphi Automotive Systems, Cadillac's strategic partner, it will be available first in the Seville.
For driver and passengers alike, MR technology irons out everything from serious bumps and holes to the smallest flaws in road surfaces. Vertical movements do not reach the bodywork, the passengers or the non-suspension parts of the chassis. At the same time, the driver is better informed of the actions and reactions of the car, thanks to the thorough filtering out of disruptive influences.
It functions as follows:
Sensors are monitoring the profile of the road surface, providing MR with a permanent stream of information. Using this data, the electronic MR unit sends currents to electromagnetic coils housed in the dampers. It does this continually. The varying magnetic fields in the dampers dictate the flow properties and the viscosity of the Magneto-rheological or MR fluid. The strut response is lightning-quick - up to 1000 times per second if necessary, meaning there is no time lag. This makes MR technology ten times faster than other modern systems.
Thanks to the elimination of electromechanical valves, MR technology is virtually silent in operation and is also wear-resistant and maintenance-free. MR dispenses with the need for costly sensors. Instead, it makes use of existing sensors to detect speed and displacement at all four corners of the vehicle independently, as well as the steering wheel and braking input from the driver. The intelligent control unit is able to preselect different driving modes by analyzing the driving style. With a dynamic driving style the control spectrum is therefore far more progressive than with conventional cruising.
As a stand-alone system, MR offers tangible improvements in stability, handling and ride comfort. But the true impact of MR technology is felt when it is linked with other chassis control systems. This provides the ultimate in vehicle stability control and active safety.
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