There are about 30,000 calories in a gallon (about 4 liters) of gasoline, which is enough to fuel a person for about 20 days, depending on their caloric intake. Humans burn energy quite efficiently. In fact, the average person who rides about 15 miles per hour (about 25 km/h) on a bicycle could do over 900 miles per gallon (almost 400 kpl) riding a bicycle if they could fill up on gas.
More facts about energy:
Vegetable oil actually contains almost the same amount of calories as gasoline, so if the human body only needed fuel, not nutrients, you could fill up with a few gallons of vegetable oil a month and finish the month’s diet. .
On a chemical level, gasoline and vegetable oil are very similar. Both contain long chains of hydrogen and carbon, making it possible to convert vegetable oils for use in some cars.
Fuel efficiency in humans declines rapidly with accompanying speed and air resistance. For example, in the bicycle example, going up to 10 mph faster reduces miles per gallon by about two-thirds.