Exactly. Look at the cooling duct underneath the P51 mustang. It is said that the hot air exiting the rear of the radiator actually provides sufficent thrust to overcome the drag caused by radiator itself.
note the radiator situated underneath
Actually after reading closer, it apparently added a few extra mph to the mustang's top speed.
http://www.ipmsstockholm.org/magazin...il_p51d_01.htm