When you start driving a Mercedes product equipped with “Attention Assist,” the car monitors your driving style during your first 20 minutes behind the wheel. It uses this data to create a unique profile of you. If you start exhibiting unusual patterns, the car will take notice and determine if you’re fatigued and should take a break.
If you’re not paying attention on the road, the car may stray out of its lane. That sets the system into action. Mercedes researchers found that drowsy and fatigued drivers tend to jerk the steering back in order to return into the lane. From there the system monitors how long you’ve been driving, how often you’ve been interacting with the controls in the car and takes into consideration any external causes to this kind of driving, like uneven road surfaces or weather conditions. If all signs point to a sleepy driver, the car delivers an audible alert, along with a message on the dash urging you to take a break. If you choose to ignore the warning, the alert will resurface every 15 minutes.
The feature is standard on a wide range of Mercedes cars including the relatively low-cost $30,000 CLA-250.
Volvo has a similar safety system but doesn’t monitor the driver. Instead Volvo’s setup pays attention to the progress of the car on the road. A camera mounted on the front windshield watches the lane markings and can determine whether the car is being driven in a safe and controlled way. The car even displays your current alertness level on a display in the gauge cluster. Resembling a cell-phone reception meter, the car will make an audible alert when your attention level drops below a certain reading. Unlike the Mercedes system, Volvo’s Driver Alert Control is not standard and is part of a technology package that uses the windshield-mounted camera for other driver assistance systems including adaptive cruise control and lane-departure warning.