Carmakers have been experimenting with head-up displays (HUD) in cars since the late 1990s. But early efforts have been cautious, displaying only speed and other basic information near the bottom of the windscreen. New technologies allow them to be bolder: the authors see HUD, long used by fighter pilots, as becoming a natural part of looking through the windshield, and, in some cases, being embedded on real-world objects such as the road or buildings. It is Borges’s 1:1 map come to life. Indeed, BMW already has a prototype AR windshield that overlays information onto the road surface to indicate upcoming turns.

BMW’s prototype windshield. Proceedings of the IEEE

While navigation is the flashiest application of augmented reality in cars, the technology would also make driving safer. For one thing, the system lets drivers keep their eyes on the road. But combined with sensors and cameras, the system could clearly indicate the distance between applying the brakes and stopping, warn about pedestrians or cars in the blind zone, or indicate that the driver is in danger of veering out of his lane or too close to another car.

Augmented reality can indicate braking distance, lane drifts and proximity to nearby cars, and warn of objects in blind spots. Proceedings of the IEEE

But AR brings its own safety issues. Designers would need to get the depth of vision right in order to not confuse drivers. Static head-up displays, which don’t attach themselves to the outside world, must be careful not to block any part of the windshield. And any images need to be carefully laid out to not confuse drivers.

Carmakers have plenty of reasons to feel confident that augmented-reality navigation will catch on. For one thing, they are already busy connecting their cars to the internet, installing operating systems, and dreaming up new ways to allow drivers to check Facebook without crashing into a tree. More importantly, the appetite for navigation is huge: In December, more than 374 million people logged into a navigation app on their iPhones or Android devices, according to Priori Data, a research firm. That’s far in excess of the 241 million people who logged into Twitter that month, and more than double the number of people who used Twitter from their mobile phones. What’s more, well over half of those navigation apps used were paid for.