Parts:
- Cabin Air Filters. Choose any of the brands below. I went with the Mann filters.
- Mann CUK2736-2
- Bosch C3821WS
- Meyle 64112182533 (Charcoal activated)
- Meyle 64319069927 (Paper filter)
- Mahle LAK 73/S
- Vacuum, towels, all purpose cleaner, Lysol or Einszett Klima AC cleaner.
Steps:
- Pop open hood
- Locate two cabin filter service covers. One is located on the driver side and the other on the passenger side behind the strut towers.
- Unclip wire latch circled in red below. Do this on both sides.
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| A screwdriver may be used if it is difficult to unclip. |
- Pull filter cover out towards you. Be careful not to damage the two rear plastic tabs.
- Part # 64318379627 left and part # 64318379626 right in case they need to be replaced.
- Remove old cabin air filters.
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| Old micro filter. |
- I don't think the previous owner ever changed the filters. Look at all the dusty, mold, and crap that on the old filter. Yuck! New Mann filter looks so much better.
- Clean filter box by vacuuming leaves, wiping away any dirt and debris. Ensure intake and drain holes are clear.
- Now is good time to spray any Lysol or A/C cleaner into the air box intake to remove nasty and funky smells.
  |
| Previous owner never cleaned the box so there is dust and debris everywhere. |
- Install new filters by placing them in box.
- There are directional air flow arrows on the Mann filter which tells you which side is up.
- Many filters have less pleats than before and do not fit perfectly in the air box. There may be some gaps on the side and distortion. Unfortunately, I haven't found a brand that is a perfect fit.
- Install covers by inserting rear tabs in first
- Reclip wire latches onto covers.
Notes:
You want to replace the microfilters regularly to ensure pollen, dust, harmful gases, and spores are removed from the ventilation system. Spend the extra money and get the charcoal filters for optimal filtration.
If you do not replace them, they will look as nasty as the old filters and you will be breathing all that crap. This is a 5 minute job and the filters are cheap, just do it yourself. A mechanic will charge too much to replace the filters and may not remove the debris hanging out in the box.
The filters come in pairs.
Helpful picture below. Taken from BMW Parts manual.
Here is a Top Gear clip of Jeremy Clarkson banging on the cabin air box with a hammer. Jeremy thinks it is a fuse box and Richard and James correct him.
Why:
Microfilters clean the air in the cabin of your BMW. A dirty and clogged microfilter means you and your passengers are breathing in that polluted air. Microfilters remove contaminants, pollen, pollutants from the air going into the cabin. This is the quickest and easiest jobs you can do and I am shocked that the previous owner never changed them.
Helpful picture below. Taken from BMW Parts manual.
Here is a Top Gear clip of Jeremy Clarkson banging on the cabin air box with a hammer. Jeremy thinks it is a fuse box and Richard and James correct him.
Why:
Microfilters clean the air in the cabin of your BMW. A dirty and clogged microfilter means you and your passengers are breathing in that polluted air. Microfilters remove contaminants, pollen, pollutants from the air going into the cabin. This is the quickest and easiest jobs you can do and I am shocked that the previous owner never changed them.
if you want a washable & reusable filter that increases power and MPG. 
next interval to see if there is any difference in power and MPG. A reusable performance filter may be more cost effective in the long-run, especially in dusty climates. Also, the standalone TRD air filter is a cheap alternative to the 
to dress the plastic in my engine bay. I really like the natural, low-gloss shine and how long it lasts.
. The Mahle filter has more pleats for better filtration and performance. Look at the picture below to see the difference. 
is the best air filter you can buy. The K&N Air Filter can be cleaned and re-used which saves a lot of money in the long run.
is pretty good if you don't want a re-usable filter.