Big Disclaimer #1: I do not approach wildlife.
Big Disclaimer #2: Vehicles make excellent blinds. Most wildlife photographers learn that their vehicles make one of the most versatile blinds they'll find.

Wildlife seem to tolerate the presence of vehicles as long as their occupants stay inside. In this case, several young bull elks were grazing near a turnout in Rocky Mountain National Park. As I sat with my lens protruding out the driver's side, the elk came closer and closer. As close as this appears, the elk was probably a good 25 feet away, but the reach of the 400mm lens makes it appear as though I could have hand fed him.