1940-1949 - During WWII, production of private cars was converted to military vehicles including trucks, planes and tanks. When post-war car production began again, the first models used pre-war designs, and it took a few years to re-tool for new designs.
New features for cars included power brakes, hydraulic shock absorbers (with a piston inside a sealed cylinder), powerful high compression engines, independent front suspension, lightweight chassis-less bodies, curved glass windshields, and rear windows. The Goodrich Company introduced the tubeless tire in 1948.
1950-Transistor technology introduced in the 1950s led to electronic ignition systems. In the US, the use of chrome plating became extreme, along with the obsession with styling modifications, rather than technological improvements, with now-annual model changes. By the mid-1950s, American cars had begun to feature power steering, air conditioning, twin headlamps, and wrap- around windshields. The first Fiberglass reinforced resins were used to create the curvaceous, lightweight and corrosion-free bodywork of the 1953 Chevrolet Corvette..
In the later 1950s, higher compression engines, fuel injection, better fuel, overhead valve and overhead improved engine power to weight performance. Disc brakes, less prone to failure from overheating than drum brakes, became widely used. In 1953, radial-ply tires were introduced, though initially only on expensive high performance cars. New plastics expanded the auto stylists arsenal, as did an expanded range of color schemes. Complex oil pressure gauges and ammeters were often replaced by simpler (and cheaper) warning lights.
1957 One interesting new engine design was the Wankel engine, with a single three-lobed driving rotor instead of conventional pistons and a crankshaft. First built in 1957 by Felix Wankel of Germany, in 1964 the NSU company brought out the Wankel-engined "Spyder," and a few years later, the R080. Several Japanese Mazda cars also had Wankel engines, that proved light, compact, powerful and smooth-running.
1965 - Car design was greatly influenced by the new interest in safety as well as pollution control. Many countries began to introduce speed limits. The Ralph Nader book "Unsafe at Any Speed: The Designed-In Dangers of the American Automobile " detailed resistance by car manufacturers (in particular, General Motors and its Chevrolet Corvair), to the introduction of safety features, like seat belts, and their general reluctance to spend money on improving crash safety. Cars now comply with the strict new safety and anti-pollution laws of the United States, which were gradually adopted by many other countries. Cars became even more comfortable and easier to drive, with better heating and ventilating equipment, automatic transmission, power brakes and power steering.
1973 - The United Stated passed the Clean Air Act (which has been updated several times since), which forced cars to install positive crankcase ventilation.
1974 - As a result of fuel shortages during the Arab oil boycott, the US-wide 55-mph speed-limit was imposed.
1975 - The catalytic converter was adopted for cars sold in the US to fight fuel consumption. Computers began to play an important role in car construction, handling inventories, scheduling construction, and on-board computers to monitor engine performance from various sensors located on or around the engine which adjust the fuel mixture, timing and other elements. The modern computer-controlled electro-mechanical carburetor adjusts automatically for outside air temperature.
1978 Anti-lock braking systems (ABS) were first developed for aircraft in the 1950. They use computers to automatically adjust and "pump" the brakes to prevent skidding during rapid braking. ABS was made available in better German cars by 1978, and generally available by the 1990s.
1980s - The first commercial air bags appeared in automobiles. Since model year 1998, all new cars have been required to have air bags on both driver and passenger sides. More recently, side airbags have begun to be added to reduce impact against side window glass by vehicle occupants, particularly when smaller cars are side-impacted by SUVs or pickup trucks which have higher bumpers.