Mercedes takes on drowsy driving

The system measures 70 parameters to try to gauge driver drowsiness.

When it detects a problem, it "emits an audible and visible warning in the form of an espresso cup icon and 'time for a rest' message in the instrument cluster," the company said.

"Drowsy driving causes more than 100,000 police-reported crashes, resulting in 1,550 deaths and another 71,000 injuries each year, according to the National Highway Traffic Safety Administration," Mercedes said in an announcement about the Attention Assist system.

"In fact, 37 percent of working Americans in the past year admitted to actually falling asleep at the wheel, according to the 2008 National Sleep Foundation's Sleep in America poll," the automaker said. "Those working more than 60 hours a week are four times more likely to fall asleep at the wheel."

Among the groups believed to be most at risk for driving while drowsy are young people "who tend to stay up late, sleep too little and drive at night," Mercedes said, adding that "people 25 years old and under account for 55 percent of fall-asleep crashes, with 78 percent being caused by male drivers."

Shift workers — especially those who work at night — also are believed to be more vulnerable to falling asleep at the wheel, along with businesspeople who drive long distances or have jet lag, drivers with sleep disorders such as sleep apnea and anyone experiencing fatigue.

Being awake for more than 20 hours "results in an impairment equal to a blood-alcohol concentration of 0.08 percent," the company said.

Toyota's Lexus luxury-car division introduced its own drowsy-driver warning system in the 2008 LS 600h hybrid sedan. The Lexus system uses a camera to monitor the driver's face to determine whether he is nodding off or not paying attention to his driving.

This system will warn the driver with a beeping sound if it detects inattention and the vehicle is drifting out of control. The warning will not sound if the driver turns his head but the vehicle remains safely on track.

But the Lexus system is expensive and limited to the LS 600h, with prices beginning around $110,000. The Driver Monitor System, as it is called, is part of the LS 600h's Advanced Pre-Collision System, a $6,650 option.

The Mercedes system is standard on 2010 E-class models. E-class cars begin at $48,600.

The Lexus system's camera to monitor the driver's face is mounted on the steering column. If it determines the driver's gaze has shifted from the road ahead for a few seconds, and if there is an obstacle ahead, the driver is warned (and awakened, Lexus hopes) by a chime and a flashing light on the dash.

As the car gets closer to the obstacle — such as a vehicle ahead — and the driver still doesn't react, the system will "begin to gently apply the vehicle's brakes," Lexus said.

Several new premium and luxury vehicles have this type of pre-collision system, which monitors the area in front of the car and begins slowing if it determines a collision might be imminent. But the LS 600h system is the only one that monitors the driver for signs of drowsiness.

So what to do if the system warns you that you're at risk for falling asleep at the wheel?

"Short naps and caffeine can improve alertness and driving performance," Mercedes said.

"If a driver feels sleepy, taking a 15-minute nap followed by ingesting the amount of caffeine in two cups of coffee can help ward off the effects of fatigue for a couple hours.

"A nap and caffeine is not a substitute for a good night's sleep, but they may keep a driver alert until they can get to a stop for the night."