hyperlogos.org

Fuel is what makes the engine go round, if not the world. Basically all automotive fuels are long-chain hydrocarbons, deriving their energy from the strength of the hydrogen bond.

The primary automotive fuel for commuter vehicles is gasoline, while the primary fuel for freight vehicles (including trains, tractor-trailers, container ships, and the like) is diesel fuel. But, what are these fuels actually made of, besides "dinosaur juice" (to wit: crude oil)?

The Gasoline FAQ has the answers:

Gasoline contains over 500 hydrocarbons that may have between 3 to 12 carbons, and gasoline used to have a boiling range from 30C to 220C at atmospheric pressure. The boiling range is narrowing as the initial boiling point is increasing, and the final boiling point is decreasing, both changes are for environmental reasons. Detailed descriptions of structures can be found in any chemical or petroleum text discussing gasolines.

Diesel, unsurprisingly, is much the same, although it is "heavier".

Aside from the primary fuels, there are a host of others. Many fuels are used primarily for heating, but in some cases can be run in the proper engine. Indirect Injection (IDI) diesel engines can be run on just about any fuel that isn't too volatile, as gasoline is; but they can run on a wide variety including kerosene or vegetable oil.

There are also many "alternative" fuels for gasoline engines. Unfortunately, very few of them can be utilized without making major engine modifications. Ordinary engines can even be converted to run on hydrogen; When Ford performed this feat, it took the use of both high-compression pistons and an electric supercharger to get compression sufficiently high to burn hydrogen, but it can be done. Much easier is the task of designing a vehicle which can run on E85 fuel - 85% ethanol, 15% gasoline - largely a computer change.