First head-up displays (HUD) were first used in the cockpits of the military fighter aircrafts with a little information displayed on the windscreen of the airplane. The next generations of the HUD were more complex and more info was added. Head Up displays are basically a transparent display with a data and user (pilot or driver) can still observe the terrain(the road) in front of him. The name of this application represents the ability of the user to access important data without having to turn his head left, right or up.
Today Head Up Displays are not used just in the military aviation but also in the passenger aircrafts, cargo, automobiles, trucks and other vehicles. Drivers need more than 0.77 seconds to read the usual car parameters from the dashboard. Driving with 60 mph this means that the car will travel more than 25 meters without the drivers see the road. So the HUD is not just a new cool gadget but very important safety feature.
There are number of cars with a HUD display as a standard equipment option, but also if your car does not come with HUD, you can buy it and install by yourself. If you like somebody else to do this for you, the seller of the HUDs will be more than happy to give you an options or info where can this be done professionally. The usual off the shelf HUD can offer speed display and nothing more, but lately there is some HUDs with advanced options.
In this moment there are numerous cars with a HUD like: Pontiac Grand Prix, Bonneville and Aztec, Chevrolet Corvette and etc.
The new Toyota Prius also have a Head Up Display (HUD) as an standard feature. Speed, the hybrid system indicator, and even navigation information can be projected on the windscreen just below the line of sight. It comes with controls that allow adjustments of the the brightness and position of the projected HUD image.