Volvo has come up with a camera-based system to detect the presence of vehicles in either rear blind spot. When a vehicle occupies the appropriate position, a light flashes on the A-pillar to say, "Hey, you, don't change lanes, ok?" The digital camera mounted beneath the sideview mirror continuously monitors a 31ft. x 9.8 ft. area by taking 25 pictures per second, and then calculating changes between frames. It won't work in heavy fog or snow, or when traveling much faster or slower than surrounding vehicles. Autoweek questions a few of the BLIS's attributes: first, the A-pillar warning light is convenient but it still adds an extra place to look after scanning dash and mirrors, thus requiring extra concentration. Secondly, even though Volvo claims otherwise, the BLIS continually warned of parked autos in the test car's blind spot. The system will be introduced on 2005 S60, V70 and XC70s— regular old mirrors will still be standard, but being alert and coherent while driving is apparently still an option.