In the past few years I have sometimes been in a position where it was necessary to stop a few hours at a rest area because of driving fatigue when on long distance travel overnight. 2-4 hours is what usually gets me back on the road. This has happened once or twice in the dead of winter. Should it become necessary, is it okay to idle a gasoline engine for long periods of time (more than an hour) to keep the heat warm? I've noticed that OTR diesel truck engines commonly run all night for this same reason. To all the tree huggers, yes this isn't the most environmentally friendly solution, but I'd rather do that than risk the lives of other drivers when I'm 60+ miles away from the next exit in rural Utah or elsewhere.