Anyone know why Hyundai would put a colder plug in the 2006 then in the 2007 model?

the '07 gets slightly better mileage right ? I suppose it burns hotter and more efficiently hence the different plug ?? just an edumucated guesstimate

Does it? I do know its a hotter plug. Heres a question when using nitrous they say use a colder plug now assuming I had an 07 with the same motor I would just have to use the 06 plug. So what if I have an 06 should I still go down one colder?

Yes, drop one heat range for every 75 shot of Nitrous. Less than 75 shot on the street one step cooler should be sufficient. Large amounts of Nitrous on the street require switching plugs in and out. Use a hotter plug when running only the motor and a cooler plug for nights when you decide to run nitrous.

Optimum spark plug firing temperatures are 500 degrees - 800 degrees Celsius. If the spark plug tip temperature falls below 450 degrees the spark plug is considered to be in the fouling range. If the temperature rises above 800 degrees the spark temperature is considered to be too hot and the spark plug is considered to be in pre-ignition.

As you know pre-ignition is detrimental to an engine and can ultimately lead to spark plug damage and extensive engine damage.