Sodium light is a kind of light that the eye is very responsive to, and it is perfect for illuminating roads and freeways: any one of you that has done some nocturnal driving will agree that the difference between driving with your vehicle's headlights only on an otherwise pitch black road, with driving under sodium lights is huge.
Other technologies that produce bright light (Xenon, Halogen, all those 'energy saving' graded ones etc) are IMO are to bright to be of such use. Notice this: they are very bright, shine on things with wavelengths that make them look confusing and are in all good lights if you want to be seen, but not if you want to see. In the above example, imagine that you are driving headlights only, and then you enter a patch of that country road where the community thought would save money by replacing the sodiums with the bright white new energy saving ones, that watt-for-lumen are great. Then, all that happens is that the light blinds you, and since it is not really reflected back from the road that well not only you still cannot really see (like when you were driving in pitch black) but now you have a bright light on your face dazzling you
So, bright new tech lights: are bright? Yes. Make your vehicle look like some sort of inter-dimensional fearsome invader? Yes. Are effective? No. So please leave the sodium lights where they are and, if you do not hate other drivers, ban xenon lights from cars.
LEDs are good for trafic lights, as they are (kind of) directional and quite bright: however, if anyone has driven in underdeveloped countries where LEDs are now out of control and used a lot in advertising billboards (gasstations etc), will agree that it is very easy to confuse a, say, green or red light from said billboards with the real traffic light- so IMHO at least the red, green and orange leds should be regulated, especially on areas with traffic and traffic lights. Do not get me wrong, I am all into how they cyberpunk up the place, but bear in mind that you do not want some senior driver misinterpreting the local fish market's daily discounts shined on green LED letters for a green traffic light, and driving just ahead simply not registering the true traffic light and running you over (or worse). Not to mention problems in computer driving.
Finally, since there has been some progress in 'naturalizing' the 'white' LED color, it will be interesting to see if this progress is to the point where light reflect back from the street is in a manner that makes the surroundings look crisp, and aids the driver in being aware of them, which is the whole point.