Well I was doing some energy unit conversions for work. And well decided to find out how much energy is 40kWh. Well 2,000 Calories (kcal) is about 2.3 kWh of electricity. So after about 17 days you consume a full Model S battery pack, this would get you about 10 miles. It only takes 10 days to consume a LEAF battery pack. Another way is 40kWh is 34,000 kcal, the Calories that you eat. An 'Outback Steakhouse Aussie Cheese Fries with Ranch Dressing' is 2,900 Calories, so 12 of them will power your Model S roughly 160 miles. I don't think people realize how much energy is in their food.