In Example 2.2 it is shown that gasoline costs nearly twice as much per Btu as does natural gas.
Gasoline is liquid under atmospheric conditions, meany it offers a much more dense energy storage.
This also means it is easier to transport, which gives a considerable range to the car. Compressed natural gas can be used with almost the same range, but the infrastructure is not nearly as developed. Gasoline is very readily available almost anywhere, while compressed natural gas for vehicles is only available in select locations. It has been estimated that a person can perform continuous manual labor at a power of 50 watts for an 8-hour working day.