Electronic Stability Control (Part 2) Serious Safety and Still Fun
If you read Part 1 of the blog on Electronic Stability Control (ESC), you know that ESC is a vehicle safety system that protects drivers and passengers from potential rollovers or unstable vehicle conditions. It is standard or optional on 218 2007 models. While the system can be a lifesaver in inclement weather or during evasive driving maneuvers, there is another side to ESC that appeals to driving enthusiasts. Automakers such as Ferrari, BMW, and Chevrolet (Corvette), among others, tune electronic safety systems so they don't detract from the driving experience on the racetrack. In fact, in some cases, these systems can actually enhance the experience and improve lap times on the racetrack.
For example, on its $350,000 599 GTB Fiorano, Ferrari provides a multi-position "manettino" switch on the steering wheel that allows drivers to choose from five settings: snow, reduced traction, sport, race, and off. Thanks to quick-acting magnetorheological shock absorbers—which apply an electric field to magnetic particles in the shock absorber to control fluid movement—the vehicle's behavior can be changed at the touch of a button. Variables like ride stiffness and the threshold at which the stability system intervenes can be adjusted easily with the manettino.
For snow and wet weather, the first two settings provide the most protection. Sport mode allows some wheel slip during aggressive driving before the system intervenes. Race mode is appropriate for track use only. It allows spectacular tail slides (oversteer) and intervenes only at the last possible moment if the system determines the car is headed for trouble. The car also features F1-Trac, an evolution of basic stability control. Based on pre-programmed parameters, the system determines which car control techniques (reduction in throttle, brake application, etc.) should be used to obtain the fastest lap times during track use.
BMW provides on all its models a stability control system called Dynamic Stability Control, or DSC. The system has three levels of operation: fully on, which is the default mode when the car is started; traction off, which keeps the stability control on but disables traction control; and all systems off. The fully-on mode provides an added layer of safety in the event of driver error or poor road conditions, controlling for understeer or oversteer by applying the brakes at individual wheels, reducing the throttle, or even engaging ABS. For example, if you are entering a freeway onramp and hit a patch of water or ice, DSC can intervene, often without the driver's notice, to prevent loss of vehicle control. DSC takes over and, all the driver notices is a flashing light on the dash indicating that the system is protecting the driver from a potentially dangerous situation. Without DSC, the vehicle would likely spin out of control.
The second mode—traction off—removes the traction control function but leaves stability control engaged. This can be useful when starting in snow or ice. With all systems fully engaged, progress would be painfully slow or non-existent in very low-traction situations, so in some circumstances it is helpful to have a small degree of wheelspin.
On a racetrack, this mode appeals to the enthusiast driver because it allows the rear of a rear-wheel-drive car to slide (oversteer) within set parameters. Although this certainly isn't the fastest way around a track, it is the most fun. And with the stability control still functional, the system will intervene should things get seriously out of control. When the system recognizes situations that may lead to a complete spin or off-track excursion, ESC will intervene.
The last mode—all systems off—is appropriate only for expert drivers on a racetrack. The only safety system still functional in this mode is ABS, which only works when the vehicle is moving forward in a straight line. If the vehicle is sliding completely sideways or spinning, ABS will not work. In this mode, the only thing that can prevent drivers from a complete spin or wreck is their skill with the steering wheel, brake, and throttle.
In the Corvette, Chevy also offers three modes for the stability control: fully on, traction control off, and all systems off. However, Chevy adds a "competition mode" that allows wheelspin and oversteer within certain parameters. Chevy recommends that drivers not use this mode on the street.
With these safety systems either fully or partially engaged, drivers can explore the limits of their vehicle's traction capabilities in relative safety. For drivers with more experience—enough to counter-steer and react extremely quickly to a sliding vehicle—the systems can also be turned off. But beware; these systems are there for your safety, so never experiment on the street. Save that for the racetrack.
