Even in the colds of South Dakota the outside temp would have to be seriously below freezing before you need to start worrying. your engines always going to need cooling rather than heating up. modern cas like the tt are well equiped to maintain a constant even when you give the car gas for long periods you should find there is limited difference in temp rise because at the half way mark the fans should come on for as long as neccesssary and as long as the radiator is in good working condition with coolant it will always cool very effectivley.
