There are a lot of myths and folklore associated with spark plugs; my impression is that factors ascribed to spark plug brand and type (smoothness, fuel economy, power, etc.) are usually caused by something else. I've heard there is a web site (sparkplugs.com?) that does a good job of explaining the pros and cons of the different types of plugs. You might want to do a search to get some general information to help guide your decision as to type and brand. Good luck.

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2003 X5 4.4i
1992 Porsche 968
2007 328i
2014 Subaru Forester XT