While I dislike going to get gas, there are merits to keeping your tank at least half full.
- In the case of a natural disaster, it's important to have enough fuel to get out of town. Since there isn't enough capacity for everyone to fill up at once, even the threat of a gas shortage will cause people to overwhelm the system.
- It's better for your car. Having at least a half tank prevents unnecessary stress on your fuel pump and fuel filter and it prevents condensation from forming in the fuel tank.
- It's more economical (especially if you buy gas when it's cold out). Because gasoline evaporates at around room temperature, with more room in your fuel tank, you'll experience reduced pressure in the fuel line. So, keeping a full tank leads to better gas mileage.