Why the design of car and submarine is of oblong shape?

The oblong shape of cars and submarines is primarily for aerodynamic and hydrodynamic efficiency. In cars, the streamlined shape reduces air resistance, improving fuel efficiency and overall performance. In submarines, the oblong shape allows for smoother movement through water, reducing drag and making it easier to control the vessel at varying depths. Additionally, the oblong shape provides more internal volume for passengers, cargo, and equipment while maintaining stability in motion.