When we think of automotive lighting, our first thoughts often go to high-performance headlamps, bold taillights, and running lights that create strong branding statements. While these trends continue, LEDs are also used as general ambient lighting. What started out as an indicator light application has given way to slick-looking backlit displays, practical-minded occupancy detection and all manner of ambient lighting based on attempts to affect occupant mood, the time of day, and other environmental factors.  Here, ambient lighting refers less to instrument panel lighting than to the indirect interior illumination that gives the driver a sense of orientation and spaciousness as well as feelings of safety, comfort, and even a sense of pride in value. Ambient lighting delivers an emotional atmosphere and, according to carmakers, ties together exterior and interior lighting conditions for the driver for decreased levels of driving fatigue.  Ambient lighting is now incorporated into innovative turn- and brake-lighting applications, backlit displays, occupancy detection, night vision, and more. Lighting can actually make us feel differently about our driving and ourselves. Ambient lighting makes a statement as well as an impact on the driving experience.

The Psychology of Color and Light People are used to evaluating the color of light in home and office. There is a real impact and psychological effect of warm or cool lighting in our environment that relates to eye fatigue, wakefulness, circadian rhythms and mood. For example, yellow light is seen as warm and pleasant, while bright white light is seen as clean and efficient. Automakers have determined that color and lighting can go much deeper than a mere visual impression. A variety of emotions can be encouraged with certain hues. BMW engineers and the Lighting Engineering Group at Ilmenau University of Technology in Munich conducted a benchmark study on automotive interior lighting in 2009. The study involved a series of questions answered by participants after driving a real but stationary car with ambient lighting in a simulated environment. Tests performed involved changes in lighting color, luminance and the position of lights in a simulated driving environment. The emotional states of the participants were gauged at the beginning and end of the tests. Elements within the study included design aspects (such as shape and material) and design principles (such as intended sportiness or luxury.) Purely functional aspects were also considered. Some participants were exposed to blue lighting and others to orange. The results showed that the blue lighting appeared brighter than orange lighting; drivers were able to find automotive control buttons and knobs easier in blue light, and blue lighting also gave drivers a better feeling of their orientation in low-light conditions. The downside of blue lighting was that it was considered "uncomfortable." In comparison, orange ambient lighting gave the perception of luxuriousness and better quality. With increasingly brighter levels of light, participants became more distracted and asked to be able to control it. Results also found that carefully designed ambient lighting can decrease night-driving fatigue and is important for brand identity. Ambient lighting was shown to enhance night-driving safety and increase appreciation of the vehicle. The study indicated that ambient lighting can enhance the perception of spaciousness and quality of materials.  Today's Applications LEDs are used in ceiling dome and map lights, backlit instrument panels, displays, controls, gear sticks and in door-panels to assist the driver as he or she enters, exits, and operates the vehicle. Interior lighting provides indirect illumination and provides a “wow factor” for design. To date, many studies have researched the effects of lighting on mood, emotion and perception in buildings. Several studies exist on the effects of lighting on vision or safety in automobiles, but to date, a BMW study from 2009 has provided the most information regarding the psychological effects of automotive ambient lighting. Mercedes, Jaguar, and Land Rover are using LED ambient lighting to differentiate their vehicles. Mercedes offers a choice of seven colors with five dimming levels and four diming zones. LEDs are also evolving with technology as exterior automotive headlamps. LED in headlamps have not only greatly lengthened life and increased efficiency. LEDs are much more flexible than incandescents in how they are able to automatically adapt to surrounding ambient light, and they are so small and light weight that they can be mounted with adhesives, screws, clamps, solder, or via any means that enables heat to adequately and evenly dissipate away from the LED. Newer, tougher semiconductor materials such as Galium Nitride (referred to as a “wide band gap” material ) enable operation at higher temperatures and with greater energy efficiency than LEDs of just 10 years ago.