Shifting Gears is a comprehensive automotive history that reaches back to the birth of the internal combustion engine in Europe and the first cars developed there. The gasoline engine and early automobile designs gradually make their way across the Atlantic to America. The bicycle had already made that journey, creating an army of bike mechanics that soon turned their talents to building automobiles. Over the next century, over 2,000 different automobile brands would come and go in the United States. The narrative focuses deeply on Henry Ford and his company as well as the stories of the other key pioneers and their cars - Buick, Chrysler, Studebaker, Jeep, and Oldsmobile - running all the way up to Elon Musk and Tesla.

The image on cover of the book is a Ford Model T with the author's grandfather at the wheel, taken at his small farm in the Midwest. The story of the impact of the automobile on his way of life is overlaid on the larger automotive history. The contrast between life before and after the automobile is stark. The age of the horse and steam power yields to the first gasoline engines, the first automobiles, and then the first tractors. World War II interrupts, car manufacturing is halted, and the surviving car companies produce other internal combustion machines (Hellcat fighter planes, Sherman tanks, and Jeeps), which are used by the next generation of the family in the war effort.

The end of the war sees a roaring return of the automobile, now sporting fins, chrome, and ponderous size. In the ensuing decades, the number of automobile makes shrinks to three, and even those left teeter on the brink of bankruptcy with the electric revolution on the horizon. The automobile has decimated the small farming towns in the Midwest. And, the fourth generation of the family is now in New York City and Chicago, and making do without a car.