With HID I am pretty sure you use less amps than a traditional halogen, but it also doesn't make as much light as an LED.
If I can get the LEDs to behave as low beams the power draw is going to be about 14 watts per lamp.
The projector head light housings with H4 halogen bulbs were around $40 when I bought them 2 years ago, the LED H4 replacements I just picked up were $68. I didn't get the cheapest ones out there. I specifically founds ones that had a large metal heat sink and did not have a ballast resistor.
Why, because I would like to be able to do more EOC with the head lights on. It wont be long before I leave to go to work before sun up and don't leave work till after its already dark.
I have found LEDs are a good answer to solving vehicle power generation and lighting issues. When I originally switched to LED tail and running lights one of the main reasons was because the factory style 1157 bulbs are dim, other drivers couldn't see them when I was driving into the sun rise or sun set, then having to stop, slow down or turn I had herd screeching tires behind me several times. Then at night while sitting at a stop light with my foot on the brake the combination of head lights, tail/brake lights and running lights was depleting the battery. Switching to LEDs saved at least 8 amps while my foot was on the brake, with lights on. That was enough to keep the system charging voltage above 13 volts while sitting at a stop light at night.
Instead of switching to a larger alternator I installed LEDs.
Then after almost backing into my old ladys car one night I added additional LED to the reverse light housing. The traditional 1156 reverse lights were kind of dim, the white 1156 LED replacements were very directional so I added a G4 LED array to the inside of my tail light housing.
DIY: Super bright reverse light mod for any 73-91 style tail light - Diesel Place : Chevrolet and GMC Diesel Truck Forums