While I think a 1/2 hour is not really needed, I think some of you are looking at this in terms of how cold it is near you. When you come out in the morning and the temperature is single numbers or lower, do you think you might need to warm up your car a bit longer so that it's warm inside as well as warm in the engine? I ran mine the other morning about 10-15 minutes because I like getting in the car with it somewhat warmed up, I had to get some of the 1/4" ice coating off the car, and it was
this cold.
Up in Canada, it's been -10 to -20 in areas....I'd say a 1/2 hour in that isn't all that crazy in thos conditions...