Does setting the air conditioning in a car to a higher level affect the gas mileage more than setting it to a lower level, or use more refrigerant? If you have a hybrid car with no payments, 50,000 miles and you're looking to get a 4 wheel drive car for snow, would you go ahead and trade in the car now while it's worth more or wait and keep not having a car payment and then trade the car in later (higher mileage, less money)?