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How Brake Assist Works

The Reason for Brake Assist

Considering all of the other braking features already available on a typical car, why would a driver even want brake assist? What if the electronic gizmos that activate it get a bit too sensitive, leading to jerky stops every time the driver taps the brakes? Auto enthusiast magazines have long railed against these electronic "nannies" that take much of the skill -- and the thrill -- out of driving.

In a word, brake assist is about safety. Simply put, research shows that most people are too wimpy with the brakes in an emergency. According to Mercedes-Benz, 99 percent of drivers either failed to apply full brake pressure, or applied brake pressure too late, in an emergency stopping situation. When Mercedes introduced the technology to the market in the late 1990s, the company said brake assist helped shorten stopping distance by 45 percent. Even skilled drivers benefited from stopping distances that were 10 percent shorter [source: Mercedes-Benz]. In practical terms, shorter stopping distances mean fewer accidents.

As for the powerful braking action coming into play when you don't want it to, the engineers sought to make sure that doesn't happen. Brake assist is what automotive engineers call a driver-adaptive system. In other words, the electronics that control brake assist measure and monitor the driver's normal driving patterns, including application of the brakes. The system can actually tell the difference between slowing down at a traffic light and making a panicked stop when a child runs out into the street.

Automakers have been known to occasionally resist new safety features because of their added cost. However, it was Mercedes-Benz along with parts supplier TRW/LucasVarity that invented brake assist and started offering it on their cars [source: Mercedes-Benz]. The technology first appeared in the consumer market in 1996, with the introduction of the Mercedes-Benz S-Class and SL-Class models. In 1998, the company made the feature standard on all its vehicles. Since then, several companies have offered their own version of brake assist, including Acura, Audi, BMW, Infiniti, Land Rover, Rolls Royce and Volvo.