It never fails. You load Fido into the car, head off to your destination and the little guy has his nose pressed up against the glass as he whimpers for freedom until you crack the window. Then he sticks his big dopey head out of it for the entire trip.

Why do they do that? Mental_Floss has the answer.

The web version of the popular information magazine said that not much scientific research has been done on the phenomenon. However, dog behavior experts believe it may have more to do with their innate sense of smell.

Dogs have huge olfactory membranes in their noses with a massive power to sense and pick up smells. Humans have the same membrane but it's much smaller and not nearly as strong as those in dogs. The membranes in humans only have five million receptors but the ones in dogs have a whopping 225 million receptors.

Air helps facilitate the process of receiving different smells. Basically, as air moves over the membrane, the more scents the dog can pick up. And as any dog owner knows, pups love to smell just about anything. Even if it's the noxious fumes from the highway. So the next time your pooch wants to stick his head out the window, remember that he's just trying to get his smell on.