What are Auto Start/Stop Systems?

A relatively new feature in vehicles is the auto start / stop system. Just as it sounds, this system automatically shuts down and restarts a vehicle’s engine, with the intention of reducing fuel consumption and emissions. This system is available in both hybrid-electric vehicles and gas-powered vehicles.

In most vehicles outfitted with this technology, when you come to a complete stop, the engine will shut off; when you remove your foot from the brake pedal, it automatically restarts. A study by the Society of Automotive Engineers found that using start-stop can improve a vehicle’s fuel economy by over 8% in heavy traffic; the engineers that Edmunds interviewed gave a similar estimate of a savings of anywhere from 3-10%, depending on driving conditions. That fuel savings can really add up - and it’s good for the environment, too. According to Edmunds, “It boils down to this. If your car usually manages 20 mpg in the city, it could earn 22 or 23 mpg if it had a stop-start system.”

Auto Start/Stop technology requires a uniquely made starter. Many people wonder if a start/stop system will wear out a starter. The easy answer is, “No.” Starters in vehicles equipped with this new tech are made differently. These starters are optimized to turn the motor more slowly, which increases its longevity. Additionally, they’re made with somewhat different materials including the carbon and copper brushes and needle bearings instead of oil-impregnated bushings. The electrical load is also reduced in these starters. So wearing out your starter is not a concern.

Other vehicle alterations are necessary for auto start/stop systems to work smoothly, too. The battery has to be heartier; it must have deep cycle capability that can withstand more frequent draws from the starter. Also, the engine’s crankshaft and rod bearings need to have low-friction coatings to handle the extra loads placed on them due to the frequent restarts. Furthermore, the entire electrical system is laid out differently in order to allow the vehicle to effectively “shut off” without turning off the stereo, fan, lighting or wipers. Some systems even stop the shut down if temperature sensors detect the cabin is getting too warm, allowing for the air conditioning to remain on. This all requires specific software not necessary in a vehicle without an auto start/stop system.

These start/stops are intended to happen seamlessly. Engineers have timed some restarts at under 500 milliseconds (that’s less than a half of a second). The most effective and efficient vehicles are quiet, with low idle vibration so as to make the start/stop less noticeable. It’s been noted by experts that hot weather and the use of air-conditioning not only use more fuel, but also make the start/stop more obvious. Inching forward in traffic typically ruins any gains you might have made had you let the car rest completely. Sitting still, with your foot on the brake is the best way to save fuel with the auto start/stop system.

All of the major manufacturers have auto start-stop technology available among their model lines and learning to drive with the technology doesn’t take long to get used to. If you’re interested in trying it out for yourself, visit the Folsom Auto Mall and take a test drive.