LEDs with outputs up to single digit watt ranges might get 100 lumens per watt (or maybe up to 150ish today) but you can pretty much halve that for those used in high powered applications like car headlamps. The thermal junction temperature totally destroys the efficiency in a spectacularly non-liner fashion. This is pretty much a given where packaging is tight such as in a car.
In fact they are very probably less efficient currently than xenon or other gas discharge technology. The reason for LEDs vs xeon is cost and simplicity both in manufacture and the fact they don't require a 600v ballast/inverter. Far more durable and easier to handle at too, while still giving the higher colour temperature. At the lower end of the second hand market, I'd actually regard xenon lamps as a negative feature, especially on mass market cars.
I wouldn't write-off halogen yet. The vast majority of new cars still rely on this technology and probably will for the foreseeable future. You can even improve the efficiency by running them "hotter". This is (at least was until LED technology came good) common for bicycle lights - running a 12V bulb at 13.2 or 14.4V. Philips sell the xtreme-vision range which pretty much do the same thing at 12V. You lose of course in bulb life.
I discovered the car I bought had been converted and I can't say the headlamps are that noticeably inferior to my 2013 VW other than the less focused hot-spot. I fact my P6 headlights are hugely better than those of the 1998 Audi A4 I had before (which for some reason were spectacularly bad).
I'd rate the headlamp upgrade as top of the list of P6 improvements.
In fact they are very probably less efficient currently than xenon or other gas discharge technology. The reason for LEDs vs xeon is cost and simplicity both in manufacture and the fact they don't require a 600v ballast/inverter. Far more durable and easier to handle at too, while still giving the higher colour temperature. At the lower end of the second hand market, I'd actually regard xenon lamps as a negative feature, especially on mass market cars.
I wouldn't write-off halogen yet. The vast majority of new cars still rely on this technology and probably will for the foreseeable future. You can even improve the efficiency by running them "hotter". This is (at least was until LED technology came good) common for bicycle lights - running a 12V bulb at 13.2 or 14.4V. Philips sell the xtreme-vision range which pretty much do the same thing at 12V. You lose of course in bulb life.
I discovered the car I bought had been converted and I can't say the headlamps are that noticeably inferior to my 2013 VW other than the less focused hot-spot. I fact my P6 headlights are hugely better than those of the 1998 Audi A4 I had before (which for some reason were spectacularly bad).
I'd rate the headlamp upgrade as top of the list of P6 improvements.