I also had a look and came up with these links:
http://www.scstatehouse.gov/code/t56c035.php
http://www.arcticbreeze-truckac.com/content/no-idle.html#NO
Both of those apply to diesel trucks, probably the same as you found.
I can’t find any link where is says you can’t warm up your car in SC. Therefore I don’t understand the reference to SC in the second paragraph of the article.
“”””The following states do not have “no idle” regulations enacted in their jurisdictions as of our latest information:
Alabama, Alaska, Arkansas, Idaho, Indiana, Iowa, Kansas, Kentucky, Louisiana, Michigan, Mississippi, Montana, Nebraska, New Mexico, North Dakota, Ohio, Oklahoma, Oregon, South Dakota, Tennessee, Vermont, Washington, West Virginia, Wisconsin, Wyoming.”””””