- The Washington Times - Friday, March 1, 2002

So frustrating. And so stressful. Driving along crowded highways, speeding up, braking, speeding up, tapping the brakes again constantly reacting to the erratic drivers ahead of us. Now some new technology, called adaptive cruise control, is offering to do that braking and accelerating for us.

Adaptive cruise control is much more sophisticated than the cruise-control function that many of our vehicles have. Instead of simply maintaining a set cruising speed, which is what cruise control does, adaptive cruise control helps maintain a preset following distance from the vehicle in front.

"The system is automatically managing all of that, so that we don't have to fool with it," said Robert D. Ervin, head of engineering research division, University of Michigan Transportation Research Institute.

Although these systems have been available in Japan and Europe, Mercedes-Benz was the first in the United States with what it calls Distronic adaptive cruise control (coined from the words "distance" and "electronic") when it introduced the 2000 S-Class. Now it is available as a $2,875 option on S-Class sedans and CL-Class coupes. It will soon be available on the new 2003 SL 500.

Lexus has Dynamic Laser Cruise Control available on the LS 430 as part of its Ultra Luxury package, which at $12,485 includes an array of luxury options, including the air suspension, moon roof, navigation system and heated/cooled front seats.

Infiniti will offer its Intelligent Cruise Control on the 2002 Q45 and QX4 as an $800 stand-alone option. BMW will offer adaptive cruise control on its luxury 7-Series in the United States sometime this year. Expect to see adaptive cruise control trickle down to less-expensive Toyotas and Chryslers in the near future, Mr. Ervin said, following the example of anti-lock brakes, traction-control and skid-control systems.

Using adaptive cruise control, the driver chooses a desired following distance to the vehicle ahead. Systems use either radar or laser sensors generally mounted in the front grille to send out signals that are then reflected back from vehicles up ahead. This information is used to automatically slow the vehicle to maintain the following distance that the driver has preset.

Just how adaptive cruise control slows the vehicle varies with the system. All systems start by backing off the gas pedal, using the engine to slow the vehicle. They vary the accelerator pedal more than regular cruise control would and slow the vehicle more noticeably. It is the equivalent of 3 percent of braking, although the brakes aren't being used. After that, systems differ in the way they slow the vehicle even more, if needed.

The Mercedes system, for example, automatically applies up to 20 percent of maximum braking to slow the vehicle in order to maintain the desired following distance. Mr. Ervin said that 95 percent to 98 percent of the time we don't need more than 20 percent of full braking to manage what is happening in traffic around us. Others, such as the Lexus system, back off the throttle, downshift the gears, and then apply the brakes.

When more braking is needed, these systems warn drivers that they need to intervene. The Mercedes system, for example, warns the driver to take over with a flashing red triangle in the instrument panel and an audible beep. Although these systems are a form of crash avoidance, they are not crash-avoidance systems in the way government and the automotive industry define them.

First, adaptive cruise control systems are limited in the braking force they use; second, they are part-time systems that the driver must turn on.

True crash-avoidance systems would be full-time systems that, without being activated by the driver, would detect a possible collision and automatically apply some braking, and maybe even steering, to avoid the crash.

Until we have true crash-avoidance systems, the benefits of the current adaptive cruise control systems are to make driving more relaxed and less stressful, especially on long trips. "And in modern life most people are standing in line to have stresses relieved," Mr. Ervin said.


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