Google's early prototypes started with stock cars from current manufacturers and lately they've been releasing pictures of their own design which looks like a smaller Volkswagon with windows in all of the normal places.

Daimler, though, understands that they have an opportunity to throw away the old rules and they've been muscling into the picture with the Mercedes-Benz F-015, a futuristic concept car that looks like a silver kidney bean. To the outsider, it's often hard to tell if there's any windows at all because the glass is coated to have the same silver gloss as the metal. The riders, though, can still see out a big front windscreen and slim side glass. But Daimler doesn't seem to think the passengers will spend much time actually looking out them. A number of the photos from the company emphasize the way that four passengers can sit facing each other, talking, working or playing games, all while ignoring the outside world.

If they do look out, they're just as likely to see the big touch screens on each door—screens that seem bigger than the slim windows. These can let anyone take control of the car— Daimler calls it "conducting"—and also pull up any other images.

The sales literature from Daimler certainly anticipates that the riders will be like the early astronauts, promising us "a continuous exchange of information between vehicle, passengers and the outside world." But one video shows a man rolling through the desert in the southwest while the touchscreens display imagery of the Louvre in Paris. It's not a car, it's a "digital living space" that provides "a perfect symbiosis of the virtual and the real world."

If the riders will be immersed in the touch screens and tablets as they roll through the world, is there any advantage to real windows? Aside from letting the passengers watch the scenery and feeling like they have some chance to control the vehicle, there's not much that the glass offers—and much that it detracts.

Standard glass is not as strong as steel and so the designers must compensate for the glass when desiging the frame. If there's a crash, the glass offers no protection. (Though the way that it shatters into a million tiny pieces is considered a step up from the way that crashes used to produce flesh-ripping shards.) In the winter the glass offers little insulation and in the summer, the windows let in too much heat, heat that must be removed by the air conditioner.

The windows also offer no privacy, letting anyone see in. If the riders really want to know where they're going, they can watch a video feed from the car's many cameras displayed on some tablet or wall screen. These cameras may even have zoom lenses and so the screens and tablets could offer a better view with greater detail than the old windows. (A movie thriller will undoubtedly include some plot where the people inside are fooled about their destination with a hacked video feed.)