Limit the amount of time you let your vehicle's engine run in the garage, and keep the garage door open. An idling vehicle emits twenty times more pollution than one traveling thirty-two miles per hour. There are sixty-five million garage owners in the United States. If 10 percent of garage owners were to idle their cars for just five fewer minutes per day, the total savings would be 84.5 million gallons of gas a year, enough for a million people to drive an average size car across the country.