What is a Start-Stop System?

Hybrid vehicles designed with a start-stop system completely shut down the engine when the car is stopped to conserve fuel and reduce emissions that pollute the environment. Electronic devices determine when the driver is coming to a stop or idling, and automatically turn off the engine. The vehicle restarts by depressing the clutch in vehicles with manual transmissions, or moving a shift level in cars with an automatic transmission. Start-stop systems have proven effective in congested city driving.

These energy-saving systems use a starter generator instead of the typical alternator and starter combination found on conventional vehicles. Electronics built into the cars regulate the starter motor on a combustible engine with a start-stop system. Electricity is drawn from a battery to restart the engine as soon as the drive pushes the clutch, moves the shift level into the drive position, or presses the accelerator.

These vehicles are commonly called "micro-hybrids," but do not use battery packs like hybrid electric cars. The start-stop system previously only appeared on vehicles with manual transmissions. Automobile designers perfected the design to include cars with automatic transmissions to save fuel in stop-and-go traffic and city driving with multiple traffic lights. The system can be de-activated by a control on the dashboard.

Manufacturers of hybrids using a start-stop system estimate substantial savings on fuel for those who mainly drive in cities. The benefit to the environment from decreased air pollution has not been accurately measured. Some countries offer discounts on purchases of hybrid vehicles, including those with a start-stop system.

Although hybrid vehicles conserve fuel and decrease air pollution, they have been criticized because they pose a danger to blind pedestrians and children. Electric cars are essentially silent at low speeds and do not provide a warning to the blind, who rely on sound to know when a vehicle is near. Studies have shown pedestrian accidents increased after the emergence of electric cars. In some regions, hybrid vehicles must add a sound device to improve pedestrian safety.

The start-stop system is just one innovation in hybrid cars developed over the years. The first electric and gasoline engine was invented in 1901 by Ferdinand Porsche. He designed a generator run on gas that delivered power to several smaller motors. The basic concept of Porsche’s gas and electric auto is still practical, but improved technology led to better fuel efficiency and better performance of hybrid automobiles.