Call NGK directly and see if someone can explain the differences. Even if they last 100k, I'd rather only spend $40 instead of $200 if no one can explain any discernible difference besides a part # variation. If NGK can give you concrete evidence otherwise, I'd be buying from Amazon or whoever has the best price all day long. Of course Amazon isn't going to list some 16 digit blah blah blah number BMW uses. Last time I did spark plugs on my 740iL, I ordered them from Auto Parts at AutohausAZ - OEM Auto Parts - Discount Replacement Parts, Resources and Car Care Tips and they've worked perfectly fine.

After watching an episode of 'How It's Made', I'd NEVER pay $20 for a spark plug. I've higher powered, turbo charged cars that demand more from their plugs than the M62 and I've never paid that much, ever. At some point you have to draw the line at manufacturer propaganda and just plain common sense.

My 7 came w/ completely different OEM tires that what I'm using now. Just because it came OEM, that doesn't mean its the best of the best. I really don't see this as any different.

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