Spur gears are the most common type of gear they have straight teeth and are mounted on parallel shafts. The main reason for the popularity of spur gears is their simplicity in design, easy manufacturer and maintenance. However due to their design spur gears create large stress on the gear teeth.
Spur gears are known as slow speed gears. Spur gears are seen as noisy due to their design so if noise is not a problem spur gears can be used at almost any speed. Spur gears are noisy because every time a gear tooth engages a tooth on the other gear, the teeth collide, and this impact makes a noise.
Spur gears can be found in applications like washing machines and electric screwdrivers but due to the noise you will never find them in your car.