Iridium spark plugs may offer the best performance outright of any type of spark plug available, but the drawback is the high initial cost. To remedy this shortcoming, Bosch offers the Platinum IR Fusion spark plug.
As its name suggests, this spark plug features a center electrode made of a Bosch-exclusive blend of platinum and iridium which is designed to increase performance over a platinum spark plug without demanding the cost of an iridium one. This is combined with four precisely gapped yttrium-enhanced ground electrodes for a more powerful spark, which allows more thorough ignition of the fuel/air mixture.
These spark plugs are designed to last their entire life without needing gap adjustment or other maintenance. If you believe that the increase in performance and durability is worth the couple extra dollars over traditional spark plugs, the Bosch Platinum IR Fusion is your best bet.
One of the main benefits of using iridium in spark plugs is its extremely high melting point at nearly 2500 degrees Celsius. The Denso Iridium Power spark plug takes full advantage of this attribute by using a fine-tipped 0.4 mm diameter electrode in place of the more traditional wide-diameter offerings. A standard electrode of that diameter would more than likely melt after prolonged use, but the Iridium allows for a more precise, controlled spark-to-ignition process.
Combined with Denso's exclusive U-Groove pattern ground electrode, this allows the Iridium Power to handily outperform its competitors. However, this performance comes with a premium price tag. At more than three times the price of a standard spark plug, it's hard to make a case for the average, casual driver. If you are a performance enthusiast or a long-distance commuter, the cleaner burning capability and potential for increased fuel economy with the Denso Iridium Power may be worth looking into.
NGK is a highly trusted brand among spark plug manufacturers, to the extent that the vast majority of automakers today choose to equip their cars and trucks with NGK spark plugs as original equipment. The Iridium IX is a good example of how well-sorted a modern iridium spark plug can be, with the small-diameter iridium electrode offering powerful yet controlled spark. This results in a more thorough ignition, and can reduce or eliminate surging and other ignition-related engine problems.
As with many other high-tech modern spark plugs, the NGK Iridium IX is a low-maintenance design that you can install and forget, though it is prudent to check the condition of the spark plugs every once in a while. Though the NGK Iridium IX spark plugs are designed to last and perform well throughout their life, the high price tag is something to consider.
Aside from being an excellent overall spark plug, AC Delco Iridium spark plugs are used as original equipment in premium and high-performance products from GM. Thanks to the higher melting point that the iridium electrode offers, this allows a more powerful spark that would wear out standard spark plugs. The powerful spark ensures a thorough ignition of the fuel/air mixture, meaning your engine will run much cleaner and smoother.
The AC Delco Iridium spark plug requires little to no maintenance, though it’s always a good idea to check gap spacing every once in a while if you suspect that the spark plugs are becoming worn. These spark plugs are rated to last 100,000 miles, and will offer substantial performance for the entire duration of their service life.
For the vast majority of drivers on the road today, the Bosch Platinum +4 can be considered the best all-around spark plug. The Platinum +4 achieves its high performance by employing four (as opposed to one) yttrium-enhanced ground electrodes. This creates a powerful, long-duration spark which is better suited to igniting the fuel/air mixture in any engine, high performance or not.
This spark plug requires no gapping or maintenance - you can simply install these in the engine and 'forget' about them until the next time you need a tune-up. The price of the Bosch Platinum +4 falls neatly in between a traditional spark plug and Bosch's own Platinum IR Fusion model, meaning that these performance spark plugs can even be considered relatively affordable.