Spearmint essential oil can be used wherever Peppermint would be used and is believed to have a less powerful effect, perhaps making it more suitable for children, the elderly, etc.
To keep a clear head, try 2 drops of Spearmint, 1 drop of Rosemary and 1 drop of Eucalyptus in a burner or diffuser. The same essential oils are ideal for use in the car - Absolute Aromas stocks AromAbout, a car aromatherapy diffuser. Alternatively, place the drops of essential oil onto cotton wool and leave in the car.