Abstract: An auxiliary air preheater means is for use in prewarming interiors of vehicles having engine preheating means employing a heated fluid for prewarming the engine prior to operation of the vehicle engine and the vehicle heater normally associated with the vehicle engine and includes an insulated housing surrounding a section of conduit employed for conveying heated fluid employed in the engine preheating operation. Air is circulated through the housing in contact with the heated fluid conduit and is blown into the vehicle compartment. Air may be returned from the vehicle compartment through the auxiliary air preheater housing for recirculation through the passenger compartment.