Spark plug OEM BMW or Denso

Fitting a decent set (Denso or NGK) of iridium plugs is also worthwhile.

I almost went 200000 km on my bmw between spark plug changes, and the motor runs so much better after. My fuel economy almost doubled, and performance was a night and day difference

Denso 3457 (FXE24HR11)

Why? It's the plug recommended in the owner's manual and I have never seen anyone have issues with this plug.

Why are they noticeably better than other equivalent plugs from reputable brands, I honestly don't know as it seems that the differences should be negligible. Plugs are one of the areas where the car is very fussy.

I finally changed out the OG Denso spark plugs on my wife's '10 RX350 at a shameful 415,000 kms. Wasn't idling rough but some low-rpms hesitation. Plugs still basically worked fine, though.

Toyota sounds like great deal if they actually use OEM plug (DENSO iridium). That part alone is \\~$18 each (you need 6).

DENSO , Iridium Long Life, SK20HPR-L11 Spark Plug

I already replaced the spark plugs with the Denso ones I listed though... Is this bad?

So i just ordered a pack of 4s (the left one is from Denso Japan) from a local distributor carrying Denso spark plugs and of the 4, 3 are made in China and 1 is made in Japan. Comparing them side by side, the China ones definitely look subpar to the naked eye.

I highly recommend avoiding anything other than exactly what is specified in your owners manual, I currently have bad gas mileage because I was too curious to see if the desno two tip would do as good as the other stuff.

I dug factory installed spark plugs out of my recently departed E90... they looked like something from the stone age. 19 year old car, and from what I could tell, never had the plugs changes.