Well,here is discussion i have to jump in(H).My friend jz has mentioned that iridium is not good economy wise.But why?The explanation is not there.
If you are using the heat range specified with copper or iridium or platinum or double platinum or titanium.it will not decrease the fuel economy what so ever.
The precious metals are used to give a point spark which will increase the ignition focus,the size of flame kernel will be bigger with the use of precious metal.remember at high rpm,the cylinder turbulance greatly affects the flame kernel.The platinum and iridium have different melting points,iridium is harder than platinum.No company has mentioned any where,that iridium is not good for fuel economy.I will be greatful if jz give me any reference.The OEM plugs in pakistan cars are copper due to price factor.Have you ever seen copper plug in any imported car?Never.They use iridium to keep them running for 100,000km.
and increase fuel efficiency of engine.Recently the european countries have introduced new laws about carbon emissions.In order to meet the law requirements,the engines have to give average of at least 22km/litre.The companies are in search of more advanced plugs to have a perfect combustion situation.
Why honda is using iridium plug in civic reborn in pakistan and getting very good average, if iridium is not good