<p><strong>Fan blades in the world's largest automotive wind tunnel stand astride a lone technician in General Motors' Warren, Michigan, technical center—site of research aimed at helping GM meet the new worldwide demand for vastly more fuel-efficient cars.</strong></p><p>In the United States, the Obama administration is soon to set mileage standards that will force automakers to double the average efficiency of their fleets to 54.5 miles per gallon (23 kilometers per liter) by 2025. The European Union is driving beyond that goal, enacting carbon emissions limits that will require new car fleets to achieve 57.4 mpg (24.4 km/l) by 2020. Canada, Japan, China, and South Korea also ramp up standards starting in 2015.</p><p>(Related Photos: "<a href="http://news.nationalgeographic.com/news/energy/2012/08/pictures/120817-shell-eco-marathon-2012/">Students Design Super-Efficient Cars in Eco-marathon</a>")</p><p>Technology for this global efficiency leap is being developed in laboratories like GM's Warren research center, <a href="http://history.gmheritagecenter.com/wiki/index.php/File:WhereToday.jpg">described</a> at its 1956 opening as "where today meets tomorrow." The slogan applies well to the fuel economy research under way more than a half-century later. The next generation of cars will look much like today's, but will weigh less, have better aerodynamics, and smarter systems that can ramp power up or down as needed.</p><p>"Most of the technology that we need for 2025 is already here," said Michael Omotoso, senior manager of global power train for the research firm LMC Automotive. "What needs to change is reducing the cost of the technology."</p><p>Hence, the importance of the work being done beneath this fan, 40 feet (12 meters) in diameter, made of Sitka spruce capped with soft balsa wood, which propels wind around the lab at speeds up to 138 miles (222 kilometers) per hour. As air currents course around the lab's 750-foot (229-meter) loop, engineers test and tweak wind resistance on new designs. Reducing aerodynamic drag by 10 percent—by say, changing the shape of a side mirror or the angle of a corner—can deliver fuel savings of 1 to 2 percent.</p><p>And in the years ahead, every fractional boost in efficiency will count.</p><p>—<em>Josie Garthwaite in Warren, Michigan</em></p><p><em>This story is part of a special series that explores energy issues. For more, visit <a href="http://greatenergychallenge.com">The Great Energy Challenge</a>.</em></p>

Tunnel to Tomorrow

Fan blades in the world's largest automotive wind tunnel stand astride a lone technician in General Motors' Warren, Michigan, technical center—site of research aimed at helping GM meet the new worldwide demand for vastly more fuel-efficient cars.

In the United States, the Obama administration is soon to set mileage standards that will force automakers to double the average efficiency of their fleets to 54.5 miles per gallon (23 kilometers per liter) by 2025. The European Union is driving beyond that goal, enacting carbon emissions limits that will require new car fleets to achieve 57.4 mpg (24.4 km/l) by 2020. Canada, Japan, China, and South Korea also ramp up standards starting in 2015.

(Related Photos: "Students Design Super-Efficient Cars in Eco-marathon")

Technology for this global efficiency leap is being developed in laboratories like GM's Warren research center, described at its 1956 opening as "where today meets tomorrow." The slogan applies well to the fuel economy research under way more than a half-century later. The next generation of cars will look much like today's, but will weigh less, have better aerodynamics, and smarter systems that can ramp power up or down as needed.

"Most of the technology that we need for 2025 is already here," said Michael Omotoso, senior manager of global power train for the research firm LMC Automotive. "What needs to change is reducing the cost of the technology."

Hence, the importance of the work being done beneath this fan, 40 feet (12 meters) in diameter, made of Sitka spruce capped with soft balsa wood, which propels wind around the lab at speeds up to 138 miles (222 kilometers) per hour. As air currents course around the lab's 750-foot (229-meter) loop, engineers test and tweak wind resistance on new designs. Reducing aerodynamic drag by 10 percent—by say, changing the shape of a side mirror or the angle of a corner—can deliver fuel savings of 1 to 2 percent.

And in the years ahead, every fractional boost in efficiency will count.

Josie Garthwaite in Warren, Michigan

This story is part of a special series that explores energy issues. For more, visit The Great Energy Challenge.

Photograph by Jeffrey Sauger, National Geographic

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