Heads up Display (HUD) also requires a special windshield. This type of dash display projects information such as vehicle speed, signal lights, and warning lights onto a special area of the windshield. To the driver, the projected display appears to float in the air outside the car, but it is actually just projected on the windshield. HUD allows the driver to monitor important vehicle information without having to take their eyes off the road. Early windshields built for HUD had a small transparent projection screen in the lower drivers side of the glass. The latest windshields look like regular windshields but the glass in the area of the projections has been tested for optical clarity. As can be expected, these windshields cost more than the standard unit.www.canadiandriver.com

Unless this overstates the need for a special windshield the laser may be required... It also seems that many of the HUD's currently manufactured are for aviation. Also isn't it true that a laser is either on or off? So the laser would be as bright at night as during the day with no real ability to dim.