Do just one thing
If you're going to the mall this weekend, make the effort to park your car in a shaded spot under a tree or inside a parking garage. Shade helps keep your car cooler, which means you won't need as much air conditioning to cool down the car when you return. Keeping your car as cool as possible naturally also helps to reduce the evaporation of gasoline in your gas tank. Gasoline evaporates all year long, regardless of what season it is, but the hot summer months are the worst for gas loss. So even if there is a spot right at the entrance to the mall in the bright, hot sun, park further away in the shade -- and you'll save gas, money and get a little exercise, too.