the energy in one gallon of gas is also enough to keep your smartphone running for how long? 30 days? 300 days? 3,000 days? the answer is... 3,000 days. because of gasoline's high energy density, your car doesn't have to carry as much fuel compared to other energy sources. take the energy quiz. energy lives here. take the energy quiz. so i tri take the energy quiz. ed depend so i it really made the difference between a morning around the house and getting a little exercise. hi-ya! and i tried a baking class.