In the meantime, the car's other safety systems can prevent you straying from your lane or getting too close to the car in front.
But there's more to it than that. Driver sensing also has other, less safety-orientated benefits. By recognizing the person sitting behind the wheel, the car could feasibly organize the car's various adjustable features -- seat, wheel, mirrors -- to that particular driver.
Okay, so plenty of cars do the same with a mere button press, but that's not very 21st-century, is it? More unique is the ability to adjust the car's exterior lighting in the direction the driver is looking, taking adaptive lighting to a whole new level.
Volvo notes that these systems aren't capable of photographing the driver, nor do they have a "surveillance" function, so even if your car recognizes you, it's only appreciating your good looks. Volvo has already installed the various systems in testvehicles, so it may not be far from reality.
More pertinent still, the technology could eventually serve a purpose in autonomous cars, determining whether a driver is ready to take the wheel again before the autonomous functions cede control.