These scents can be added to windshield washer fluid to change the aroma of the fluid when it is sprayed. Simply add some of the scent to a gallon of windshield washer fluid, shake, then add it to the vehicle.
With windows down, it will provide the aroma of choice when spraying the washer fluid and will be extremely noticeable.
With the windows up and the vent fans on, there will be a lighter version of the scent that flows into the vehicle.
One small bottle can scent up to 4 gallons of windshield washer fluid.