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One More Way to Save Gas and Reduce Emissions

John Day

John Day

Posted Dec 10, 2013

Bosch is touting a new start-stop system that it believes will someday – and probably sooner than later – be as common in cars as air conditioning.

Start-stop with coasting.

The company says tests it has conducted shown that combustion engines runs needlessly about 30 percent of the time, which means that a car could just coast for about a third of the way from here to there. Under real traffic conditions, Bosch estimates, the start-stop coasting function could help to reduce fuel consumption by 10 percent.

The technology stops the engine when the vehicle is in motion, so that it does not consume any fuel.

“The start-stop coasting function is affordable, can be combined with any type of combustion engine, and substantially reduces fuel consumption,” says Dr. Rolf Bulander, member of the Robert Bosch GmbH board of management.

Bosch says the coasting technology requires few additional components and can be integrated into just about any vehicle in the world.

Whenever the vehicle can maintain its speed simply by rolling – such as on a gentle incline – the engine is stopped. As soon as the driver touches the gas or brake pedal, the engine starts up again.

Vehicles with double-clutch transmissions have a “light” version of the coasting system that switches the engine to idle as soon as the driver takes his/her foot off the gas. But Bosch’s system actually stops the engine – as soon as the driver’s feet are off the gas and brake pedals.

Besides saving gas, the start-stop coasting system reduces CO2 emissions. Bosch estimates that if the three million new vehicles sold in Germany in 2012 drove an average of 11, 500 kilometers and each vehicle had start-stop coasting technology there would be 10 fewer grams of CO2 emitted per-kilometer, resulting in a CO2 reduction of more than 30,000 metric tons.

Reduced fuel consumption also means lower CO2 emissions. In Germany, some three million new vehicles were sold in 2012. According to statistics, the annual average distance driven is around 11,500 kilometers. If every new car were equipped with the coasting system and emitted just ten grams less CO2 per kilometer as a result, the theoretical annual reduction in CO2 would amount to over 30,000 metric tons.

What makes it work? Bosch credits “enhanced software” that makes better use of sensor data.

CO2 reduction, reduced fuel consumption, sensor data, start-stop coasting

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John DayJohn Day recently launched John Day’s Automotive Electronics News ( to provide news and feature coverage of the automotive electronics industry. Earlier he wrote for Auto Electronics magazine, Auto E-lectronics, EE Times, and other business and engineering publications. Visit John Day

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