The 1157 led lights at autozone and pepboys are no good. Regular 1157's are 300 degrees or so of light, 90% or so of the light produced, is reflected to the reflector lens of the light fixture. These "ricer" type of led lights have a Very Narrow angle ((45 degrees), and little to no light actually hit the reflector, resulting in no light, other than a star. It is particularly hard to even tell your brake lights are working during the day! That is why they are Illegal! On the packages it says "for offroad use only" or "For show use only", so they can sell it.
I have bought Auto-zone led lights before and saw what it does. Also they don't work well with running lights in my experience. Had to throw them away. I've seen them on cars and trucks round here and it really hard to see their taillights. Get wide angle LEDs instead.
85 Chevrolet. 30 MPG or bust!
The 1157 led lights at autozone and pepboys are no good. Regular 1157's are 300 degrees or so of light, 90% or so of the light produced, is reflected to the reflector lens of the light fixture. These "ricer" type of led lights have a Very Narrow angle ((45 degrees), and little to no light actually hit the reflector, resulting in no light, other than a star. It is particularly hard to even tell your brake lights are working during the day!
That just shows that there is more variance in LEDs than there are in normal car bulbs. I know for a fact that there are cheap/junk LEDs, and that there are also very good LEDs out there. Without a lot of standards, you have to shop very carefully for what you get.
For example, I went with the Luxeon 1157 modules from http://www.superbrightleds.com for my tail/brake lights (and I also used amber Luxeon modules for my turn signals). These modules aren't that cheap (I got them for $20/each, but now they are $25/each after a price increase). However, those modules have a 130 degree angle, and the entire 130 degrees sees light (and since that light comes from a single super bright LED, it is NOT a star pattern, but is instead a true cone of light). As a result, pretty much the entire car lens gets filled, and the light is actually BRIGHTER than stock 1157 bulbs (as long as you put a red colored Luxeon behind a red lens, thereby avoiding the light loss you normally get when you start with white light and then use a colored lens). So if you hunt around, you can get LEDs that actually work BETTER than the stock bulbs.
BTW: To get back to the OP's question, LEDs are a judgment call as to being "worth it" or not. They do help save electricity, and that does lower load on the engine, resulting in slightly better FE. But it's unclear if the extra FE will pay for the LEDs over the life of the car. But OTOH they also have other advantages, including almost never wearing out, potentially crisper easier to see light (depends upon the LED module used), etc. I remember my wife got two different "written warnings" about burned out lights, before we put the LEDs in her Civic (and part of the reason we did the LED upgrade, was to avoid having bulbs burn out in the future, and therefore forever more avoiding that hassle of having to prove to the cops that the light is now fixed). And it is true that a complete LED upgrade (except for the headlights) can be done for under $300 (I think I spent about $200/car) even with very high end LED modules. So it's not as if it's an extremely costly upgrade either.
Like Dracofelis pointed out, Led's are not all created equal. Some are very bright and others are so dim you can hardly see them in daylight.
Eventually LED's will be used everywhere including light bulbs for your house but I would not bother with them on my car unless you want them for style points.
Now on my boat trailer LED lights are awesome! I replaced all the original glass bulbs with sealed LED fixtures that are super bright and don't have a problem being dunked into salt water. Regular lamps on a boat trailer are one major pain to keep working, and I have not had to touch my LED setup for over two years now. Worth every penny!
I replaced all the rear lights in my metro with leds. Not for FE but saftey. With regular bulbs the whole lens did not fill with light. Now with leds they do they are a full square. I also let them flash at the faster rate, people seem to notice them better. Do a search on the local auction site there are lots of types. The ones I bought have leds projecting in all angles. The industry is going to them for lots of reasons. One is there are lots of lights so you have more if one burns out. Also with the extreme elect. loads every little bit helps.
The matrix (http://autolumination.com/matrix.htm) style of led light bulb has 18 leds pointing up, but ONLY 6 to the sides. Seems to me you would want it the other way around. Otherwise the red light would be concentrated in a 1 inch circle, and not fill the whole reflector bowl so you see the whole light fixture lit up. OR does the red plastic lens bend the light so it is lit up??? There are many different led lights to choose from. I don't know which work properly. Could some of you who have led lightbulbs post a picture to show how it looks?
85 Chevrolet. 30 MPG or bust!