Buick introduced the Series 40 in 1930 as a replacement for the Series 116. The Series 40 rode on a 118-inch wheelbase and powered by a 258 cubic-inch six-cylinder engine which produced 80 horsepower. Braking was through mechanical drums found on all four corners. The suspension was comprised of semi-elliptic springs and Lovejoy hydraulic shock absorbers. During its first year, there were six bodystyles to select from, including a Sedan, Sport Roadster, Business Coupe and Special Coupe in two-door configuration. A Phaeton and Sedan version were offered with four doors, with the four-door sedan with seating for five being the most popular bodystyle on the Series 40. Pricing was rather competitive, starting at $1260 and continuing through $1300. The Phaeton had seating for four or five, and had the lowest sales in the Series 40, total just under 1000 examples.

The name 'Series 40' remained dormant for a few years, making its re-appearance in 1934. They were again Buicks entry-level vehicle, though much had changed in these few short years. The Series 40 lightweight vehicles powered by an eight-cylinder engine that measured 233 cubic-inches and produced nearly 100 horsepower.
For 1934, the Series 40 rested on a 117-inch wheelbase and had an entry price of a mere $795. The top-of-the-line Series 40 would set the buyer back $925. The four-door Club sedan continued to be the most popular of the Series 40, selling nearly 11,000 examples in 1934. Five body styles were available, including a two-door Touring Sedan, Sport Coupe, and Convertible Coupe.

For 1935, little changed. A few extra colors were added and the trim was revised slightly. Mechanical problems from the 1934 Series 40 were resolved, such as clutch and timing chain issues. A new bodystyle was added, the Convertible Coupe.