re: the graphic found here under the title "Which NGK Spark Plug Is Right For You?":
More Information for NGK 1483
What is the diff between "Performance/Ignitability" and "Efficiency/Fuel Economy" ? I would have assumed there would be direct correlation between them, i.e. better performance == better efficiency. But at least for Iridium IX vs Iridium Laser, that seems to not be the case.
Any thoughts?