As a photo nut, I just wanted to add in a word about how aperture and focus play a role together. To a very good approximation, the depth of field is about 1/3 in front of and 2/3 behind the focal point. For a car facing towards you, if you got a DOF of about 2.5 meters, you'd want to focus somewhere around the front of the front door to get the whole thing in focus. DOF also depends on focal length, focal distance, and (as mentioned) aperture. For certain shots, you can make it appear as if you have a greater DOF by using a long (telephoto, aka high-zoom) lens.