LED Lighting is often not suitable for this kind of use. It is only in recent years that is has been approved for use in road vehicles, and only a few years before that were High Intensity Discharge (HID) lights approved. Before that there were quite strict guidelines on what could and couldn't be used on road vehicles. A non approved modification to HID or LED in a road vehicle is an MOT failure, you can also be stopped and prosecuted at the side of the road. I believe one of the rules is (It was when i was doing tests) that with a HID light there must be an automatic self levelling system to minimise the risk of dazzling other road users. Of course, if you modify a car without this then you will not necessarily have this system.
Emergency vehicles and LED blue lights is a current topic i am interested in. I find their use unacceptable on many occasions. To have the rear facing lights of an emergency vehicle (that is not parked) at full brightness at night is highly dangerous and i would not be surprised if there are not already incidents that have this partially to blame. There should be (and i am led to believe there is on at least some vehicles) an option to limit the brightness of these when necessary.
LED Technology has moved on hence its more frequent use in road (and rail) vehicles but what is also important is not how bright it is but the
colour temperature. Varying CTs reflect off of different surfaces in a different ways. Higher colour temperature (more daylight colours, 6000k + often referred to as cool white) Are good for some things, but are more prone to dazzling oncoming traffic as they will reflect off of a shiny surface more prominently, wet roads being an obvious example. They are also poor in fog. A lower CT (More like an old tungsten lamp, 3400k give or take, often referred to as warm white) gives better illumination in foggy conditions but can appear to be less bright for a given output. This is why you'll often see front fog lamps on road vehicles utilising traditional lamps and even yellow filters. Of course this is often pointless as most road users are completely unaware of how and when to use front fog lights so their benefit is removed.
Slightly OT. In the theatre we often favour LED sources for some applications due to their flexibility, long life, and low current consumption but whilst technology is improving, a good old fashioned tungsten lamp has the "warmth*" that people expect to see on the stage.
Even more OT . There is lots of concern at the moment that generic tungsten lamps that have already been prohibited for sale for domestic use in the UK will soon be prohibited in the theatre and entertainment industry too.
