The Car of the Future

Steer, Stop: The last bastions of mechanical linkage fall.

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MORE BY WIRE The new Saturn VUE, top, features all-electric steering; the Mercedes SL500 has electric brakes

When you hit the brakes on the new Mercedes SL500,
the car takes it as a digital recommendation, not a physical order. Mercedes has managed to consolidate most modern brake-control features into a single, integrated unit it dubs the Sensitronic brake system. The heart of the system is an electrically powered, high-pressure hydraulic supply that can apply considerably more force, more quickly, than an old-fashioned foot, even with power assist.

With an array of digital sensors, the system can time how quickly you are moving your foot from the accelerator to the brake pedal: A quick move arms the brakes for a panic stop. If you then stab at the pedal as if you mean it, the brake takes over and hits with full force. Cornering, the brake shifts pressure to the outside wheels, where there is more grip. If the car starts to spin, it finds a single wheel to add pressure to correct the slide. Finally, if you approach the car ahead too quickly, a Doppler radar in the grille sees it coming and slows the car.

Of course, most normal braking actions do not awaken the system's override, but the driver will want to avoid sudden, jerky braking moves.

At the other end of the technology spectrum is the new Saturn VUE, a sort of sport-utility vehicle that has
an elegantly simple electric power steering unit. A powerful DC electric motor is attached to the steering shaft
via a worm gear drive. In this configuration, the belts, pumps, and boosters of most power steering units are all gone. The complexity is found in the VUE's new software, which can be programmed to change feel, speed, and steering power.