I was shocked to know that a car would break down in minutes without it's cooling system. This means to me that the cooling system is indeed a vital component in the automobile system. The most interesting design of this system in my opinion, is the radiator. The fins available have be shown to increase the heat transfer exponentially if optimally designed, under the right conditions. For example if gases are used for cooling, the fins will not be necessary as it would not cause a significant loss of heat. On the other hand if the effectiveness of the fin does not justify the cost, it is therefore by design principles not worth it.
Fins basically increase the surface area. Hence heat loss according to this formula;
Q = hA(Ts-T∞)