Car Head-up display explained
A head-up display or heads-up display—also known as a HUD—is any transparent display that presents data without requiring users to look away from their usual viewpoints. The origin of the name stems from a pilot being able to view information with the head positioned "up" and looking forward, instead of angled down looking at lower instruments.
Although they were initially developed for military aviation, HUDs are now used in commercial aircraft, automobiles, and other applications
General Motors began using head-up displays in 1988 with the first color display appearing in 1998 on the Corvette C5. Nissan offered a head-up display in the 240SX from 1989–1994. Toyota, for domestic market only, in 1991 released this system in Toyota Crown Majesta. In 2003, BMW became the first European manufacturer to offer HUDs. The displays are becoming increasingly available in production cars, and usually offer speedometer, tachometer, and navigation system displays. Night vision information is also displayed via HUD on certain General Motors, Honda, Toyota and Lexus vehicles. Other manufactures such as Audi, Citroën, Saab, Nissan, and Kia currently offer some form of HUD system. Motorcycle helmet HUDs are also commercially available.
Add-on HUD systems also exist, projecting the display onto a glass combiner mounted on the windshield. These systems have been marketed to police agencies for use with in-vehicle computers.