Alfred Sloan, who had come to GM with the Hyatt Roller Bearing Company, took the raw material that Durant had assembled and made it run. Clearing the way for a decade of expansion and technical innovation, Sloan replaced Durant’s erratic, one-man leadership with clearly formulated policy and talented executives. Some GM cars had competed for the same markets; to prevent that, Sloan gave each car division its own price and style categories. He also introduced annual model changes, creating a market for used cars. Sloan took over from Pierre Dupont in 1923 and led the company for 23 years, until 1946.

GM began planned research, development, and testing of products in the 1920s, and reached a number of technical milestones: the 1923 Buick’s four-wheel brakes, the 1926 Cadillac’s shatter-resistant safety glass, chromium plating, automatic engine temperature control, hydraulic shock absorbers, automatic choking, adjustable front seats, and numerous advances in performance, dependability, and manufacturing technology. Costs fell as volume increased.

GM engineer Charles Kettering developed Duco lacquer, an exterior body paint that not only gave richer, longer-lasting colors but reduced drying time –erasing a huge limitation on production capacity. Before Duco lacquer an auto maker producing 1,000 car per day needed 21 acres of covered space to hold 18,000 cars while they were undergoing drying and finishing, which took three weeks. Duco reduced drying time from 336 hours to 13 ½ hours (and eventually to minutes).

Purchases and investments in new plants in Europe, Australia, New Zealand, and South America made GM a prominent international company. New plants included Vauxhall in England, Opel in Germany, and Holden in Australia.

Until the late 1920s, car design had been fairly well dictated by function, but GM’s Harley Earl turned it from an engineering feat into an art. GM President Sloan, impressed with Earl’s streamlined clay model of the 1927 Cadillac LaSalle, hired him as the industry’s first designer. Earl reasoned that since cars were motion machines, their styling should suggest their speed and power.

But styling didn’t mean GM abandoned practicality. Its trucks and buses were popular, and the K Series trucks of the 1920s gave GM its lasting reputation in the heavy-duty truck field.

The 1 millionth Buick was built in 1923; the 5 millionth GM car was a 1926 Pontiac. In 1927, GM vehicles outsold Fords for the first time.