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HANDLING THE ROAD | BRAKING AND TRACTION
Air bags, seat belts and crumple zones may save your life in an accident, but better to avoid the need for them altogether. Antilock-brake system (ABS) technology has paved the way for new safety innovations that help you maintain control in cornering situations where conventional brakes would stop the wheels but not necessarily the car. The ABS wheel-speed sensor is a critical part of traction control, electronic stability-control and certain all-wheel-drive systems, all of which help your vehicle stay on its intended path.
All-wheel-drive systems are not panaceas for all driving conditions. The systems have limited, though important, usefulness. AWD is good in two situations: under acceleration in snow or mud, where it’s priceless; and in high-performance driving, again under positive torque. Unless you drive very aggressively in slippery conditions, AWD doesn’t help in the rain. When you back out of the throttle, it does nothing. It doesn’t increase cornering limits or decrease braking distances. All-wheel-drive cars are safer, however, because they recover better in understeer situations and can take advantage of electronic stability control, since the speed of all four wheels can be computer-regulated via the brake, throttle or both.
1. Traction Control
Traction control uses the ABS sensors to determine when a wheel’s rotational speed is out of sync with the engine’s revs or the other wheels—when the wheel spins in wet or icy conditions or when accelerating—then selectively brakes the wheel and reduces power to it.
Dodge Charger. The new, sub-$25,000 Charger demonstrates how traction control is now available across the price spectrum. The sharply styled sedan comes standard with a system developed by corporate cousin Mercedes-Benz.
The Cadillac DTS puts 291 horsepower to the pavement through its front wheels. Traction control moderates power so that the driver isn’t constantly muscling the front wheels straight.
Some enthusiast drivers think traction control diminishes road feel and interferes with the car’s performance. But no need to worry—manufacturers often include buttons to desensitize the systems.
Power 250hp, 250 lb.-ft. of torque, V6
Performance 060 in 6.0 sec., 130 mph top speed
2. Multifunction Brakes
Disc brakes, which use hydraulic calipers to clamp down on rotors attached to the wheels, are quickly moving well beyond their now almost basic ABS systems.
BMW 330i. The redesigned 3 Series includes several innovative brake features, among them Brake Standby, which anticipates hard braking and snugs the pads closer to the rotors, and Start-Off Assistant, which holds the brakes to prevent rollback when starting uphill from a complete stop.
The Mercedes S-Class vehicles feature an electronic braking system, Sensotronic, that applies brake force to each wheel independently, helping retain control during panic stops, even on bumpy roads. Although it suffered early technical problems, the system has matured.
At the very least, try to avoid any car that doesn’t have antilock brakes—you can’t afford not to have them.
Power 255 hp, 220 lb.-ft. of torque, inline 6-cylinder
Performance 060 in 6.1 sec., 155 mph top speed
3. All-Wheel Drive
If road conditions cause any of a car’s wheels to slip, advanced AWD systems automatically divert power to the wheels that have grip. Working in concert with traction-control systems and limited-slip differentials, these systems shift torque front-to-rear and, in some cars, side-to-side to help maintain control.
Infiniti M35. Unlike other AWD systems, Infiniti’s version maintains a rearward bias for a satisfying rear-drive feel. In adverse conditions, though, it behaves like other systems.
The German manufacturers have been pushing all-wheel drive for a long time. Most Mercedes and Audis offer it, and Porsche’s 911 Carrera 4 makes excellent use of it as a performance enhancement.
In general, the systems add weight and cost, and they probably aren’t necessary for moderately powered cars driven in states that don’t see much snow.
Power 280 hp, 270 lb.-ft. of torque, V6
Performance 060 in 6.0 sec., top speed not available
4. Electronic Stability systems
Electronic stability systems moderate engine power and selectively apply brakes to individual wheels to stop cars from sliding out of control. Sensors compare wheel speed and steering angle to the vehicle’s rotation around its vertical axis to determine whether the car is moving in the direction the driver intends.
Porsche Boxster. The stellar Porsche Stability Management system counters wheel slippage prompted by drivers who lift the throttle abruptly during cornering—which can cause the back end to slide out—by subtly applying the gas to prevent a slide or spin.
The Mini Cooper S Works comes standard with electronic stability control. This 201hp, 2,678-pound car would be prone to spins during aggressive driving if the system weren’t in place.
These systems don’t differ much—except in how they’re calibrated—so you can be happy just knowing your car has it.
Power 240 hp, 199 lb.-ft. of torque, flat-6
Performance 060 in 6.2 sec., 159 mph top speed
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