Pressured to meet global escalating government fuel economy and emissions standards, auto manufacturers increasingly are adding engine stop-start systems across their lineups.
At its most basic level, a stop-start system automatically shuts the engine off every time the vehicle stops, such as at a traffic signal, and restarts it instantly when the brake pedal is released and fires up to take off.
During a stop, the car’s lights, radio, heater and air conditioning continue to operate.
The engine will continue to operate if the car is stopped on a hill, the steering wheel is turned or either the air conditioning or heater are working hard to maintain a desired temperature.
Relatively inexpensive for manufactures to install — around $300 — stop-start by itself can add three to five percent to mpg numbers.
The benefit of increased fuel economy can be greater for those who drive a lot on city streets, or during heavy commuting hours with frequent stop-and-go traffic.
Automakers also have a benefit, as they can receive credits toward meeting federal fuel economy regulations if they put start-stop systems on their vehicles.
By the end of the year, IHS Markit forecasts that slightly more than 15 percent of new vehicles sold in the U.S. will be equipped with stop-start, up from 5.7 percent in 2013 and 7.5 percent in 2014, the Detroit News reported.
“Five years from now, we’re expecting about 65 percent take rate on stop-start,” said Paul Lacy, senior manager of Americas powertrain and compliance forecasting for the firm.
Hybrid vehicles with automatic stop-start use a powerful electric motor that can provide instant torque to both start the engine and start the car moving from a stop.
In the past, on non-hybrid cars with stop-start systems, the engine had to be spun up to speed by the starter motor before the vehicle could move.
This resulted in a lag with noticeable shuddering between the brake pedal’s release and power being delivered, something that carmakers are overcoming.
Today’s systems are comprised of a heavy-duty starter, a more powerful 12-volt absorbed glass matt (AGM) battery, an electrically driven transmission pump that maintains internal hydraulic pressure even with the engine off, and sensors.
Some European makers, such as BMW and Mercedes-Benz, along with Ford and Cadillac, have the capability of turning the system off, while others do not.
Ford has said it would apply the technology across 70 percent of its product-line volume by 2018, while General Motors and Fiat Chrysler say they plan to substantially increase use of stop-start.
Driving a vehicle with stop-start can take some time to get used to, but remember, not only does it increase fuel economy while you are sitting quietly at a stop light, there also are no harmful emissions pouring out the tailpipe.