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Is Start-Stop in Your Future?


Drivers of hybrid and electric vehicles are accustomed to a feature called “start-stop” that saves fuel by turning the vehicle off when you’re stopped (e.g., waiting in traffic) and restarting it when you’re ready to move. However, if you want a new, conventional automobile or light-duty truck, you might consider buying one that uses the same technology. You can now find it in a range of American automobiles, including Cadillac CT6s, Chevy Malibus, Ford Fusions, and Ford F-150 trucks.

Start-stop (also known as auto start, idle stop, auto start-stop, start/stop, or mild hybrid) technology senses when your foot is on the brake for a predetermined period of time and shuts off the engine. All your auxiliaries remain on while start-stop is engaged. When you release the brake, the engine seamlessly starts up again. The technology underlying start-stop includes a heavy-duty starter that can endure 300,000 cycles instead of 30,000 cycles found in most vehicles.

Europeans have long used this technology, as their fuel prices are as much as three times higher than ours. In addition, start-stop engineering is less complicated for manual-transmission vehicles, which are more common in Europe than here in the States. Finally, current U.S. Environmental Protection Agency (EPA) fuel-economy test procedures don’t account for much simulated idling, so start-stop–associated savings may not even show up on the label of the new car, although this may change in the near future.

I recently took a few test drives of both American- and German-made automobiles equipped with start-stop. Each of the vehicles had an indicator similar to the one below to show when the feature was in use.

Indicators of start-stop technology in a 2015 Chevrolet Malibu

Indicators of start-stop technology in a 2015 Chevrolet Malibu. The left photo shows the indicator when the vehicle is stationary but not idling; the right photo shows the indicator when the vehicle is stationary and idling. Used with permission of Intertek Testing Services NA.

At first, the silence and lack of vibration at traffic lights were quite noticeable, but it didn’t take long to adjust to the quiet. Then, in the instant that it took for me to move my foot from the brake to the accelerator, the engine came back to life. I was expecting this experience, but if I hadn’t known about it, I would have been quite disconcerted. Automobile manufacturers do allow the start-stop feature to be turned completely turned off.

So how much fuel can you save by having this technology in your car or light truck? To quote EPA, “Your mileage may vary,” and savings depend on traffic and driving style. Fuel savings probably range from about 3% to more than 10% for stop-and-go city traffic. However, your driving habits strongly influence your actual fuel economy.


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