Same as others have said for truck or plane.
However I sometimes travel to range, shoots ,or even hunt locations in the wives Toyota. (Yaris, very small)
When doing this I bungee the bow unstrung to the handles over the the inside of the doors. (back to front, usually on drivers side,where the clothes hanging hooks are on most vehicles) When doing this you can travel, get in and out of the car, and never know the bows are there. Had 3 adults and 1 child in car on last trip. With three bows in this location we traveled 240 miles 1 way and nobody even took notice to the bows being in the car.