On a hot day and traveling in a car, which method of keeping the occupants comfortable with the A/C is more energy and fuel efficient?
-
Set the thermostat to a lower temperature and keep fan speed to the lowest setting
-
Set the thermostat to a slightly higher temperature and compensate by setting the fan to a higher speed so you can feel cool enough with the breeze
Aerodynamic drag increases with the square of velocity so the math checks out. Every additional 10mph is going to have a far greater impact than those before.