I do run 35W HID in my fogs on my 2007 E70.
It is not easy to get your fogs work properly.
First of all you have to code your vehicle and shutdown bulb check for fogs. Another story is that your FRM module (ECU which controls also all lights in your vehicle) has some specific settings to limit the voltage on the fog bubls in order to save their long life). You can just install the relay and make many many wires, however you may just make some smart configuration and coding of your vehilce's FRM ECU and push it not to limit the voltage. Standard limit is set for 13.2 volts for the fogs. Once voltage reaches this limit your FRM starts to cut the voltage, thus your HID will start to strobe :D Many people expiriencing this problem with strobe HID after installation but not many exactly know where to fix it :thumbup:

Regarding the temperature and power - 35W HID kit works perfect in fogs so far, temperature is OK also.

Blow the HID or halogen bulbs? I'm not sure what you mean. Even if the bulb fails in an HID setup, you still won't get a warning on the OBC because the resistor is still attached to the ballast. You'll only know something happened the old fashioned way...you wont have lighting on that side.

I did it for an upgrade since they are brighter, and since I've got projectors, the light still stays focused down to the ground, not over powering people like they probably would in the reflector style forglights. Generalize much? An improperly aimed anything can do that, you don't need HID's to blind people. As long as you're using HID's in a good projector setup, the light is actually more focused and less light is wasted vs using halogen. I now have a VERY distincy cutoff line that I didn't have before with halogens, as beforehand the light was more scattered all over the road...now it's directly in one place.

If HID's are so bad, they wouldn't be used in so many cars...the difference is when used in aftermarket conversion in the wrong housing. I put a set in my non-projector headlights on the X and they were terrible. I've seen people even do it in regular non-projector headlights like my neighbors Toyota Tacoma, F350's, etc where it's a simple reflector headlight. For the most part, those aren't designed for HID's, so the headlight suddenly looks HUGE, is overly bright vs being focused, and is then blinding for other drivers. My bike doesn't have projectors, and while the light output is far brighter and better for me, I know I'm blinding on-coming and drivers in front of me...but in that situation, I don't care becase at least now they see me.

I don't personally see many of these aftermarket HID's as an actually upgrade in adverse weather conditions. That is what the fogs are for afterall...for use in fog and rain. Brighter lights are not necessarily better in fog. Neither is a whiter or more blue light that matches your low beams. Yellow fog lights are the best in fog and rain due to the way the human eye interacts with different colors of light, so why would I want to match my fog with a bright white headlight? If you are more interested in the way your car looks or if you primarily use your fogs as driving lights, then that is another story.

I have read tons of threads on Bimmerforums about people getting codes, problems due to excess heat, etc. I know a few people here have run into those issues as well as others.

I run 3000k fogs, so I've got the yellow foglights that you're talking about. It does help in two ways since it's brighter, the beam is more focused and it's yellow.

If they're getting codes, it's because they didn't get resistors with their HID kits. I've got HID's in all my cars and not one single code from any of them. I don't know how they'd get excessive heat since an HID bulb is a gas that react to an electrical charge from the ballast vs a halogen bulb that gets hots due to current actually running through a filament, making plenty of heat. Ever touched a hot halogen headlight bulb, or replaced a bulb in your house? HID's don't get hot like that, and since it sounds like you disapprove of HID's in general, I'm guessing you're speaking from hearsay more than experience.

Adding resistors to your vehicle in order to get rid of error message on the board is not the best way to do. Coding is the best aproch in my opinion, especially because it eliminates the need of these bulky parts (resistors, relays and e.t.c.) :thumbup:

Your opinion is biased because you do coding, and while I can as well, the resistors were free with purchase. Resistors are used everyday, from the computer your replying on now and in the TV you watch in the evening...there is nothing wrong with using them in the car either. When the time comes and I remove the resistors, it won't require me taking the time (or paying someone in your case) to flash back to stock.

Do a search on Bimmerforums for HID fog lights and tell me that codes and heat are non-issues. Hell, do a search here. most of the threads are about codes or one or more HID fogs not even turning on the first try. Plus, it seems that most people on these forums tend to "upgrade" to HID fogs to get the brightest light that will match their headlights. It is worth poining out that that is not a good idea.

It hasn't been my experience, I've done HID upgrades for customers as well. What others due, their technique and/or corners cut is maybe their situation...I just know I've never had an issue in doing them for the past say 5yrs+ that I've been doing upgrades. My first set was in the 7, purchased through Apexcone about 5yrs ago. All my other sets have either been from hidextra.com or ddmtuning.com, but within the past few years, everything has been through DDM because of their lifetime warranty. The only major changes I've seen with HID's is that ballasts have gotten smaller, more reliable cold starting and their prices have come down considerably compared to when I got my first set. I've even done a H6054 to H4 headlight conversion (instead of replacing the whole headlight, it's now a modern replaceable bulb in the back) in my POS 90 S10 Blazer, and if the wiring in that old thing can handle it without issues for the past 1.5yrs, then I don't see why people are having issues in their newer BMW's. If done right, it's a win win as they also last longer than halogens on top of being brighter and more focused in the correct housing. I can't account for others experiences or installation procedures.

Agree, most of newer HID ballasts from DDM or any Chinese supplier use digital controller which is much more reliable, runs at lower current (including start-up current) and has built-in safety features.
Generally, halogen bulb runs hotter than 35W/55W HID bulb but since HID bulbs are longer especially for H1s and H3s versions, HID bulb could be located closer to the plastic parts of fog light, which may start to melt.
Sometimes HIDs start to flicker or flash because they consume less energy compared to halogen which freaks current controller in the car. This can be solved by installing resistors, relay, reprogramming or using 55W HID kit instead of 35W. 55W kit consumes about the same energy as halogen bulbs.

E53 Info

Projection housings

Left - 63178409025 - up to 06/2001 production - H3 style bulb - $112.78 @ Tischer BMW
Right - 63178409026 - up to 06/2001 production - H3 style bulb - $112.78 @ Tischer BMW
Recommend 40 mil Lamin-x film (Product# B108) while ditching the reflective lenses and retrofitting the projectors
Went with the HIDextra.com 35W H3 5K system based on James' review. Not using resistors. Haven't ran into poor visibility or overheating or flickering issues yet.

FYI.... leaving the E70 section now..... ;)