[BC Clark]

The man reason is that they are standard copper plugs. While platinum and iridium fine wire plugs offer longer life and a more open ignition area, copper is still a better conductor. This selection may be due to the fact that the coils are driving two plugs each and the copper works better. Yep there are 16 of them. A friend of mine's 2014 Chrysler 300 Hemi has a more standard tuneup interval so there is something in our application. On the bright side they are not expensive (especially if you have to buy 16), there is plenty of room in the engine bay (try a sideways FWD V6), and I have always found changing plugs quality time with my engine.

 

[BC Clark]

Out of curiosity I took a look at the part numbers of the ignition coils between the 2012 and 2014 and they are the same part number. Since the computer controls the entire profile of the spark, timing, intensity, duration, etc. it's possible that there is a different profile programmed to optimize the later style plugs. That being said it doesn't look like you will be hurting the coils if you want to try a fine wire platinum or iridium plug.

 

[BC Clark]

Well 32,000 miles came up and I replaced the spark plugs. The owners manual said NGK LZFR5C-11 so I went ahead and stuck with those. $3.32 ea. at Rockauto. And upon removing the old ones that was exactly what the factory had installed. Dead easy to get to only needed a u-joint for a very shallow angle on a couple. The bore pretty well matched my spark plug socket but no clearance issue. They were not horrible but they were ready to be replaced. I would not extend the interval but I wouldn't panic if you can't get right to it. I found using one of those part grabbers a good way to thread the new plug in by hand. So while there was nothing difficult, removing 8 coils (two screws each), removing the old plug, checking the gap on the new (they were pre-gapped but things can happen during shipping), adding dab of anti-seize, reinstalling, and replacing the coils took a fair amount of time with 16 plugs. And left a pretty amazing pile of dead plugs.