[Big time]

What about using the whole front end and undertray or at least the metallic hood and fenders as a radiator by running coolant tubes beneath them?
This way the front grill might be closed completely to reduce drag. Maybe only requiring a small opening for the AC radiator.

Of course

-This will increase weight and require more coolant.
-The front end might get too hot to touch specially for children and dumb adults.
-Body paint might hinder heat exchange and the paint itself might be damaged from heat.
-A dent might rupture the cooling tubes, spilling coolant thus needing to tow the car away.
-To open the hood some wear-prone flexible coolant hoses would be needed. BTW some insulated handles can be fitted allowing to open the hood when hot.
-Hoods already get too hot from the sun. Maybe this restricts the idea to a flat undertray.

Has this been tried or proposed before?
Maybe for airplanes or some other vehicles?