Even a mediocre sun visor is preferable to none at all.

Courtesy of Christopher Ziemnowicz

Sun visors used to be simple -- a scrap of fiberboard covered with vinyl or fabric, attached to a hinge. The hinge allowed the visor to flip down, blocking direct head-on sunlight, to the side window, or up and out of the way. Most had mirrors. The fancy ones had mirrors that would light up. And many were accessorized by the auto equivalent of a fanny pack -- a piece of ungainly slotted felt, designed to hold 8 or 9 CDs, that strapped on the visor with Velcro.

And that was it, really, and consumers seemed reasonably satisfied. As long as a sun visor blocked some of the sun's blinding rays, it had served its purpose. A mediocre sun visor was preferable to none at all. There was always room for improvement, but there was also a line that could not be crossed -- blocking enough sun to see clearly, while leaving enough of the windshield unobstructed so that a driver could see the road and avoid obstacles.

But as far as automotive designers and aftermarket electronics manufacturers are concerned, anything can be improved. Even if it turns out the improvements aren't exactly necessary. And even if consumers later discover that the improvements might not have been plausible, after all.