Funny this thread should come up... I'm actually pursuing a patent for a recent idea, a Stirling Engine based radiator. Information on Stirling Engines can be found
here on Wikipedia and
here at howstuffworks. In short, a Stirling engine converts a difference in temperature between areas into mechanical work (and vise-versa -- cryogenic applications introduce mechanical work into a Stirling engine to create a "heat pump" and keep things nice and cool).
My idea is to essentially use waste engine heat to raise the temperature of the "heated" part(s) of the Stirling engine and to use air flow/outside temperature to cool the part(s) which need to be, thus putting waste energy to good use. The Stirling engine/radiator could makes tons of parts obsolete (such as radiators and associated fluids, metal exhaust -- if the gasses were cooler, plastics could be used -- and with a bit of clever engineering, even air conditioning) and it'd be an amazing companion to the traditional ICE and probably even wind up as a component in some hybrid systems.
In fact, focusing the beam of a parabolic mirror on the heating element of a Stirling engine is (currently) the most effecient way to use solar power. They really are amazing things, sadly overlooked due to their "heat up" time and the problems they suffer due to thermal expansion. But if you want to see one in action you can search Youtube for Stirling Engine -- some of the best examples of how low-tech these can be are made by high school and tech school students -- or you can
make one yourself (I got to make something similar to the Can one back in HS physics III).
Too long; didn't read: I'm gay for Stirling engines.