Just posting some quick info. We constantly have customers ask about using LED bulbs in low-beam headlight applications, like the FR-S. I just took these shots for a customer, to show them why the LED bulbs on the market are still not a good option, even when using a halogen projector, like that found on the FR-S. Just thought some of you may appreciate this comparison!
Most companies selling these products for low beam application show very poor comparison pictures, where they are washed out so you can't actually see the beam pattern. They claim that the output is good. The real pictures below tell a very different story.
Cutoff doesn't matter.
Many companies justify that the output of their LEDs is OK, just because there is a cutoff line. Sure, you don't want light sprayed everywhere, but more importantly, you need light focused properly. As you can see, the factory halogen light is focused into a very tight beam, with a hotspot right at the center, which shines light far down the road. This is key to performance and visibility. You want all of the light focused right in the center, with a small area to the sides also illuminated, and just a bit below.
Total lumen numbers don't matter
...unless it's focused. Many sellers claim high lumen numbers, telling you the output is higher than halogen. In reality, the total output is usually about the same as halogen, and sometimes it's a bit higher. But since it is not being focused where it should be, the end result is that your visibility will decrease. It doesn't matter how much light you have if it isn't going in the right direction. As you can see, if you use an LED bulb for your headlights, you'll get some light output, but it will not shine very far down the road because it is not being focused into a hotspot at the proper location.
Just for comparison, we included a standard HID output. With HID, you get a focused beam, and a lot of light, so there is indeed a significant improvement in visibility. However, you do add quite a bit of light everywhere as well, including some on the top end. The main problem with HID is when it is installed into reflector housings, and the factory optic cannot direct this extra light properly. However, the projectors in the FR-S are quite good.
when you're looking at your low beams, an upgrade to OEM HID headlights is the best option, but an HID conversion is still a much better choice in terms of output and visibility compared to the LED bulbs on the market.
Of course, these LED bulbs are still a great option when you don't need focused light- such as high beams or fog lights. But there is still a long way to go before they are suitable for low beams.