Beginning with the mention of the earliest known wheel found in Mesopotamia from about 3500 BC and continuing through to designs of possible automobiles of the future, this thin book succinctly summarizes the development of wheeled vehicles. The first steam-powered horseless carriages were created in Europe. Inventors on both sides of the ocean then began experimenting with combustion engines. As a result of their successes, the speed and efficiency of vehicles was ensured. Diagrams detail the workings of both two-stroke and four-stroke engines. Henry Ford's introduction of the moving assembly line for the construction of cars made them available and affordable to the general public. Descriptions of the workings and parts of automobiles are followed by examples of other motorized types of transportation, such as buses, trucks, and emergency vehicles. Safety features of cars are described and ecological considerations are discussed. Full color photographs, drawings, and diagrams enable the reader to visualize the important points of the text. A glossary and an index are available for young researchers. This is part of the "Breakthrough Inventions" series.