I think Bosch super 4 plugs work on the principle that spark will initially use smallest or most convenient gap of the 4 between ground electrodes and centre pin and when that gap starts to wear it will use next smallest gap and so on and because there are 4 ground electrodes and 1 centre electrode it will slow down the rate of wear on the electrodes and so last longer without using Iridium. These 4 electrode plugs have been around for years and I did try them many years ago but didn't notice any difference in performance.
If you want to splash out now and 'fit and forget' some plugs and not have bother of changing them for 75K get Iridium ones ( can't go wrong with NGK Iridium plugs, they have nickel plated threads to stop them seizing in aluminium cylinder heads). I use them in my motorbike and combustion in bike engines is normally harsher and more challenging than in car engines, and it always starts OK and runs well.
