To put it simple, its a device used to warm up your engine block so that engine fluids flow easier during a very cold start. You plug it in for a couple hours before starting or better yet keep it pugged in but use a timer to engage it a couple hours before you intend to start it in the morning.
Google it. Lots of info.
BTW...if you have one the plug should be tucked away in the center hole of the front bumper behind the license plate. Usually an X will have it since it is intended for driving in cold weather climates.

 

Well, I lease an 08 G35, and I've driven it with both premium and regular gas and to be honest...I noticed no difference between the two. MPG has averaged exactly the same down to the tenth of a mile and I haven't noticed any performance difference between the two. I drive about 60 miles a day so it does save decent money over time running regular gas.

I'm going to turn this car in after 24 months and I don't rag on it, I keep it clean, and I'm not going to feel guilty if I run regular gas from time to time.

 

+1 LOL