Why have cars changed so much since 1950?

Technology, better lubricants, and the use of lightweight materials. Technology allowed car manufactures to install computer controlled fuel injection on engines which made engines more fuel efficient and better running. The use of plastics made cars much lighter and more fuel efficient. Disc brakes allowed cars to stop quicker. Air bags and seat belts along with built in crumple zones made cars much safer. Better lubricants and tighter tolerances on engines made them much more reliable and less prone to break down. And one important factor was the elimination of lead in fuels. All this has made cars far more reliable, safer, more comfortable, and way more fuel efficient.