Design News for Mechanical and Design Engineers

The technology, which enables vehicles to stop their engines while waiting at traffic lights, could help consumers reduce fuel consumption by 10-15 percent. Engineers from Daimler’s Smart brand of vehicles said it could conserve gasoline as much as today’s hybrids, without the high initial cost. At a standing-room press conference attended by more than 500 journalists, Zetsche demonstrated the concept on a Smart “fortwo” vehicle.

“We are trying to offer a technology that customers will buy, and will still give them better gas mileage,” said Klaus Badenhausen, chief engineer of Smart.

Despite its name, the “micro hybrid” does not use a conventional, parallel hybrid drivetrain. Instead, it employs the starter-generator (sometimes called a starter-alternator) to noiselessly stop and start the engine at traffic lights. The device automatically restarts the engine as soon as the driver takes his or her foot off the brake pedal.

In the "fortwo" vehicle, Smart employs the technology with a small, 52-kW gasoline-burning engine. The company noted, however, there’s no reason it couldn’t be used with larger engines, in larger vehicles.

“The idea is to provide better fuel consumption without an expensive hydrid drive,” Badenhausen said. “And you can’t feel any difference between this and a conventional car.”