It’s interesting to see that Audi is releasing a car with LEDs for all lights including the headlights. This is being promoted as an environmental benefit, however a quick google search revealed that my Volkswagen Passat apparently takes 55W headlights (giving a total of 110W of electricity used). Even allowing for some inefficiency in the alternator this would make a very small impact on the fuel use of a engine rated at 140KW. The Audi in question is the R8 (wikipedia link because the Audi web site is badly broken) and has a 300KW engine…
A simple implementation of LED headlights will do some good for plug-in hybrid cars and all-electric vehicles where saving power is more important – when the technology filters down to cheaper vehicles. Also one possible use for the technology is to dim the headlights by turning off some of the LEDs in the bank (according to the LED Wikipedia page it is currently impossible to create a single LED that takes more than 1W of power, so a bank of LEDs would be used). Currently you have a choice of using “parking lights” or “head-lights” when driving, and when driving just before sun-set or at night in the city (where the street lights are bright) you need head-lights to allow other drivers to clearly see you but don’t need them as bright as they have to be when driving at night in the country. So a range of levels of luminosity could be effectively used in headlights to increase efficiency in some situations and increase light levels in others.
According to the Luminous efficiency Wikipedia page current LEDs are up to three times as efficient as quartz halogen incandescent globes and future developments are likely to increase that to six times the efficiency. Combine that with more effective use of headlights to provide the light at the location and level that’s needed and the result could be using at little as 10% of the electricity for headlights on average!
Another thing that I would like to see is the Adaptive Headlights feature of the better BMWs (which I referenced in a previous post about the BM 5 and 7 series) implemented in a cheaper and more reliable manner. The feature in question is that the headlights will turn when driving around a corner to show the road ahead instead of just shining off the edge of the corner. Implementing such a feature with incandescent lights is difficult because they have to be physically turned and moving parts tend to break (which increases maintenance costs and decreases the overall reliability of the vehicle). An obvious alternate design is to have a set of LEDs pointing in different directions and which LEDs get power would determine where the light goes (this would also react faster than physically moving a light). Once LED headlights become common the Adaptive Headlights feature could be implemented in the cheapest cars on the road with minimal extra cost – currently it’s a feature that would be expensive to implement and would increase the sale price of a small car and probably the service price too.