[j12piprius]

Thanks for the feedback. It seems to me the faster acceleration with platinum or iridium plugs would result in shorter pulses for each coast, and thereby better mileage. If not, then they must burn more gas to get the faster acceleration, which becomes a tradeoff. Why would iridium plugs increase emissions or affect valve timing? Based on the comments, I'm getting the basic ngk copper plugs, the same ones recommended in the manual.