Fuel-efficient powertrain cooling systems and cooling modules

There are embodiments of a powertrain cooling system and embodiments of a radiator module for use on board a vehicle is provided. In one embodiment the drive train cooling system comprises a first air flow path, a second air flow path, a primary radiator block, which is positioned in the first air flow path, an auxiliary condenser block which is positioned in the second airflow path, and a first air flow valve, the second in the air flow path is positioned upstream of the auxiliary radiator core. The first air flow valve in which the first air flow valve prevents air flow to the auxiliary radiator core between a closed position and an open position movable.