Why do dogs like to hang their heads out the car window?
Dogs love to hang their heads out the car window. They enjoy feeling the wind smashing against their faces and ears stretching them back to the max. The must feel the freestin the hood. But not only do they feel the wind's freshness but they actually experience a myriad of sensations through their olfactory receptors. As you know, this is the most important sense have, because it is through this sense that they perceive the world surrounding them.
All this doesn't mean one has to open the window completely, with just enough to let a breeze of air come in it'll do. If one didn't do this, it would be like making them go blind, and depriving them from exciting and unknown sensations to be discovered.