One of my childhood memories is that my grandfather used to keep a little spiral bound notebook in the glove compartment of his cars. There was a little gold pen clipped to the notebook’s back cardboard. In the notebook was a log of every single trip to the gas pump. He recorded the mileage, the date, how many gallons he purchased and the price. If someone borrowed the car, they’d not only be responsible for returning the car filled with gas, but they’d also need to be sure to log their own fill-ups.