While we'd all love to see 1,000-horsepower supercars that effortlessly reach 100 miles per gallon, the pace of fuel economy improvement is far less aggressive. Automakers are scratching and clawing for every mpg they can find by doing things like downsizing and turbocharging engines, adding direct injection and variable valve timing, utilizing electric power steering and cutting weight. Another great way to save fuel is through improved aerodynamics, as evidenced by an enhancement made to the 2011 Chevrolet Cruze Eco that helps the new C-segment sedan reach 40 mpg on the highway.
The Eco Cruze utilizes an innovative automatic air shutter system that closes the grill vents at higher speeds to reduce drag by .016 – adding .5 mpg and helping push the Cruze to the magic 40 mpg number. The shutter system is fitted to sensors that measure changes in speed or temperature. If the temperature drops or the sensors measure sufficiently high speeds, the vents will be closed by electric motors, cutting down the amount of air that enters the engine bay. Why not simply keep the grill vents closed all the time? Because added airflow is needed to help cool the engine at lower speeds. Follow the jump to read the General Motors presser and watch a minute-long video that shows how the shutter system works.
[Source: General Motors]
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DETROIT – Squeezing out every last drop of fuel efficiency is one of the key tasks for Greg Fadler, aerodynamics engineering group manager at Chevrolet.
Fadler and his team worked on making the 2011 Chevrolet Cruze Eco one of the most fuel-efficient small cars on the market, achieving up to an estimated 40 MPG on the highway – hybrid-like efficiency without the hybrid cost.
Engineers used some of the proven approaches to making the Cruze Eco a gas sipper, trimming its overall weight and lowering the ride height. But the real innovation is behind the front grill where an automatic air shutter system allows the car to change shape and cut through the air more smoothly.
The air shutter system uses sensors to feel and sense wind and temperature conditions. The sensors are married to electric motors that open and close the shutters automatically. With the shutters closed at high speeds, wind drag is reduced. At lower speeds, the shutters open to maximize engine-cooling air flow. The air shutter system contributes nearly half a mile per gallon in combined city and highway driving.
The cooling systems for all GM vehicles are designed for the worst-case scenario, which is pulling a trailer up a grade in Death Valley. The shutter allows them to significantly improve fuel economy, while still providing the cooling needed in that extreme case.
"The real fun of the job is when we discover something new or innovative that allows us to do something better than we or our competition has done before," Fadler said.