Prepaid gas cards are very easy to use. You can purchase them from a variety of places.
There is no need to carry gas money in your pocket. With prepaid gas cards you can save from 5 to 10% on gas prices. For example you might pay 30 dollars for a card but you can buy 33 dollars worth of gas with it.
Note that prepaid gas card will be valid only at specific gas stations. Prepaid gas cards can be a great money saving tool.