Add air conditioning to a car
Hang a wet rag over the middle vent of the car. The air that blows through will be much cooler. Have a few wet rags ready to replace it with; they dry out fairly quickly. A passenger could be in charge of replacing and wetting new cloths.
Drive barefoot (illegal in some places). It might feel a little weird, but your body lets out a lot of heat through your feet, so traveling barefoot (or at least with flip flops) will help keep you cool.
Drive with wet hair. As the moisture evaporates from your hair, your scalp will cool off, bringing down the temperature of your body.
Add some ice. A 10 pound block of ice on the floorboards under a vent will help cool things down. This hack is derived from what residents in Arizona actually used for car air-conditioning in the 40's and 50's! To prevent leakage of water in your car, rest the ice block in a plastic pan or a baking tin. Opening a window a little will help with air flow.
Freeze water bottles to use as ice packs. Wrap the frozen bottle in a towel and put it behind your neck. Once it thaws, drink the cold water in it to cool off.
Plan your travel times to coincide with cooler parts of the day. Early morning is often the coolest time of the day, and if you're not on a fixed schedule, plan on doing as much driving as possible before the heat becomes unbearable later in the day. Try to avoid driving home mid-afternoon, to avoid the worst heat of the day.
Work with the traffic flow. This is another step in planning your travel time. Most medium to large sized communities have "rush hours", when people are on their way to work, or home afterward. This event may cause you to be stuck in bumper to bumper traffic hardly moving along at all.
Look for shady routes to your frequent destinations. If you drive a north or south direction, tree lined streets and roadways are often shady for much of the day.Roll down the windows.
- If you have a fan operated fresh air vent, open it, turn on the fan, and open a rear window enough to draw a draft through your automobile.
- Opening the car's sunroof or sliding back window will draw a lot of fresh air, even when you're traveling in traffic that just seems to be creeping along at a snail's pace.
Install reflective window tinting on the windshield and windows. This can offer a substantial reduction in direct sunlight coming into your car, and also provides some protection for the vinyl interior from UV radiation which can damage your car's upholstery and dashboards. (Note: check with your state to ensure this is legal. Some states in the USA do not allow this practice.)