A car's interior illumination used to be an afterthought, with a single dome light (and maybe a couple of reading lights in the rear) making up a vehicle's interior lights. Gradually, style became an important consideration, particularly in luxury cars. Car designers now use myriad illumination sources to create a distinct style, be it sporty or luxurious. At the same time, it has been seen that proper lighting can also increase safety. While a driver at night mainly sees the glow of the dashboard and other display systems, the surrounding internal and external environment affects perception and vision. There are oncoming headlights, rear brakes, turn signals, switchgear bulbs and ambient LEDs. Even map or reading lights.
It used to be that a car's interior was limited to purely function. These include the forwarded dashboard lights, backlit switches, and overhead and reading lights for the rear passengers. Within the last decade though, designers have begun incorporating ambient lighting, where its use is more aesthetic or psychological / emotional rather than functional. In practice, ambient lighting is made up of dim indirect lights that accentuate certain elements of the car interior, such as the doors, center console, footwell and door pockets. Most often not visible to the driver, these bulbs reflect their lighting from the interior surfaces of the car. They are also meant to remain lit while driving, and are designed to aid the driver in manipulating controls, as well as enhance the occupants' mood and alertness. Today's luxury cars already have these types of systems standard.
The use of ambient illumination was made possible by LED lighting, which give off very little heat and are very small, compare to incandescent bulbs. LED lighting has actually been in use for almost two decades as the lighting in instrument panels and switchgear. Currently, LEDs have found a new home in tail lights and are soon to be of common use in headlights.
Retrofitting your car's interior with LED lighting is a reliably easy task. The trick is how to incorporate this readily-available lighting aid into your car's interior, so that it becomes an aid instead of being a distraction. The wrong colors could also cause a driver to misjudge road obstacles in night driving, when the wrong colors affect their objective visual performance.
The advice for incorporating ambient lighting and LED lights include:
1. using diffuse lighting so that the effect is more uniform instead of being concentrated on one spot,
2. Shielding the sources of interior lights that are on when the vehicle is in motion, and
3. using small wattages so that the light does not cause glare within the interior of the car.
In the end, it is the car owner's taste and sense of practicality that will determine if the lighting upgrade is a success or not. Car customization is a very personal thing and what works for you may have the opposite effect on somebody else.