How do you drive an automatic vehicle in uphill condition?

Normally as you would drive safely anyway. On a very steep grade kick it out of Overdrive The 4Runner has a button on the gear shift. Other vehicles w/o that feature you may have to drop a gear with shifter, especially a 4 or 5 speed auto, and allow the engine to run at about 3000 rpm, so as to not 'lug' it, it will consume a bit more gas but is easier on transmission and engine. Don't forget to put it back in O/D or "D" when you crest a grade..unless the other side is equally or steeper (more steep?) downhill, and allow the engine to control your speed instead of riding brakes. If you are talking about off-roading, climbing a very steep hill slowly, put it in Low or "1"