It's not something you give much thought to. I was driving an Audi A3 in the rain last week. It was an annoying rain that ranged from drizzle to downpour every five or ten minutes. And suddenly I was noticing the windshield wipers.
Prior to the manufacture of Henry Ford's Model A, Mary Anderson was granted her first patent for a window cleaning device in November of 1903. Her invention could clean snow, rain, or sleet from a windshield by using a handle inside the car. Her goal was to improve driver vision during stormy weather - Mary Anderson invented the windshield wiper. -- about.comIn car technology, the high-end cars get fancy new features like tiptronic before the econoboxes. However, as in the computer hardware market, quality of parts in the final product improves as part volume increases and prices drop. Before long, all the econoboxes have the same cool features as the luxury cars. In fact, in some ways, car manufacturers are suffering the same difficulty in differentiating their products as computer makers. In both industries, manufacturers must build products more and more from the same building blocks as their competitors in order to optimize cost and quality.
Robert Kearns claims that he invented the intermittant windshield wiper (in 1967) and that all automakers installing this device should pay him for use of his patent. He settled with Ford and Chrysler, but recently had the suit dismissed against GM and all foreign automakers. He claims he will refile. -- Univ of TexasSo, as I was driving through the variable percipitation and forgot to toggle off the windshield wipers, I realized the wipers were turning themselves on and off, not at a set interval, but according to the intensity of the rain. Like magic. All possible because of a new optical rain sensor embedded in the windshield.
The sensor projects infrared light into the windshield at a 45-degree angle. If the glass is dry, most of this light is reflected back into the sensor by the front of the windshield. If water droplets are on the glass, they reflect the light in different directions -- the wetter the glass, the less light makes it back into the sensor. -- How Stuff Works
The first tiptronic transmissions showed up around 1999 and were available in econoboxes by 2003. I expect everyone will get optically controlled wipers by 2008 or so. If not, you can always buy a used Audi.