Spark plugs are all of the same design with a few exceptions like one of the Bosch plug which instead of the usual electrode and cap arrangement has a particular 4-point electrode construction. Let’s not get too technical and help you choose the right spark plugs for your car.
Spark plugs are available in three different materials. You will notice the difference in the materials from which the electrode and cap are made.
Cooper is the original, but not the best. Copper spark plugs are the basic and the cheapest on the market. Older engines can often run better with copper, so there is still place for them on the market.
Platinum is a good middle ground material and cheaper than iridium plugs. It provides a boost in performance and fuel economy compared to copper. Look for plugs that use double platinum both in the electrode and cap. You will notice the performance boost instantly!
Iridium is the best of the best among spark plugs. It will deliver best performance and fuel economy and has the longest lifespan, but it is also the most expensive.
Note that platinum and iridium may not always mount well in older cars and even if they do, they won’t last long in an old vehicle.