The fourth generation began in 1959 and the Bel Air underwent a major redesigning. The tailfins were made flat and wing-shaped. The vehicle was 211 inches long 11 inches longer than 1957 one and had a wheelbase of 199 inches. This recorded Chevrolet as the longest car with a low price. There was an increase in the legroom of about 5inches and an addition in the outside width of 3 inches than the 1958 Bel Air done by reduction of door thickness. To support the big body of the car the cross member of 1958 was made larger and stronger. The Bel-Air which had been ranked at the top of the line was now a middle-range vehicle. Station wagons continued to be built as a separate model but had numbers classified to match the car series.
The middle range wagons were Parkwood six-passenger and Kingswood nine-passenger with Bel Airs model numbers. A few changes were made such as decreasing compression, fuel injection, the addition of special cams, and installation of different speed options. The new Impala was doing so well in the marketing with production exceeding that of Bel Air with 20,000 units. The new option was a parking brake warning light. For 1960 a few changes were made like returning the 1958 cone tail lights and giving the car a more restrained front end. The fuel injection was dropped and with the 348 cubic inch engine, the car could achieve a horsepower rating of 35 at 5800 rpm. These required the application of three-barrel-carburetors, a special camshaft, and a compression ratio of 11.25:1 which would be sold as a single package. The body styles available were the Sedans and hardtops while the convertibles were left for the Impala model.