I bought these. Noticeably different from OEM (less pleats). I've installed them. Are they really bad compared to OEM ?

 

They're fine. People get too hung up on air-filters. There is always someone who has a horror story about this brand or that, but there isn't any consistent evidence showing that one brand protects better than another.

 

The most important thing with cheapo filters like Fram is the fit. As long as the frame fits the air box properly to create a seal and not let unfiltered air in, it is fine.

I tend to stick to OEM for that reason. The Mann filters are pretty cheap on Amazon.

 

I like K&N. I've been using them for years without any problems. I don't notice a real performance improvement with them, but they do show up to a 5% fuel economy improvement.

 

I order oil filters for my SL R129 on Amazon and I usually buy Mann filters, when the time comes to change filters on my R W251 I will probably order Mann from Amazon also.

I was introduced to the parts counter manager at my local MB dealer today by a friend that works there as a tech so I may be a good idea to start buying MB filters at the dealership. Ordered a new set of carpet mats and touch up paint today and paid slightly over wholesale so it may be a good idea to show my face for small money parts so that in the future the discount is still there for big money parts.

I have K&Ns on my SL because I polished out the throttle body and wanted to take advantage of the increased air flow ability otherwise for me the only advantage is the reusability.

 

Yes, I have been using Mann filter which made for Mercedes but cheaper for half of the price.

 

You can find Mann at a good price especially if you buy more than one. I buy Mann oil filters a dozen at a time at a cost less than Walmart's.

I do not understand why anyone would look to save money on oil or air filters. MB engineers would kill for an inexpensive way to gain HP or efficiency. In the production volumes they deal with they can spec just about anything they want. What is OEM is a result of countless hours of engineering. Most if not all of the American brands of filters (Fram, Purolator,etc) do not make products for European makes. Sure they sell filters but what is in the box can be anything from a Mann to some nameless Asian supplier. They put their business for these foreign car filters up for bid and you never know who wins the bid. This is why you can get 2 filters that are obviously different but come in the same box. Filter design is not magic, if you want less restriction you can make the filter bigger or let more dirt through. Any claims about being smaller and less restrictive are bogus. Yes, many race cars use K&N but they rebuild the engines as often as every race. The OEM air filter assemblies are designed for a specific engine and specific output most of the times. R350 owners get overbuilt air cleaners as they are designed for R500 engines. We are lucky that MB uses more conventional filter material. Some Asian makers like Honda spec advanced filter media packed into small housings to get the needed performance. There are few suppliers that are willing or able to supply filters that can meet OEM specs. As a consequence buying filters for Asian cars at your typical auto parts store is far more perilous.

As it is trying to save money on filters compared to the potential risk seems to be poor bet.