Good-bye, Gas Guzzlers

What will it take for automakers to deliver a fleet of fuel-sippers?

The road to better gas mileage isn't as difficult as it seems (© Andria Patino / Corbis)

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A Helping Hand From Computers

More than a decade after the U.S. introduction of the Prius, hybrids still make up only a tiny sliver of the overall auto market—about three percent of vehicles sold in the United States. But some of the technology in today’s hybrids could help a broad swath of tomorrow’s cars get better gas mileage. One of the most important pieces is start-stop technology, which shuts off the engine when the vehicle is at rest, and then restarts when the driver steps on the accelerator.

In hybrids, this is often combined with regenerative braking, which harnesses kinetic energy during slowing and braking to charge a battery. The stored electricity can then be used to restart the engine. “Regenerative braking and start-stop are going to be basically very common design elements in the next few years,” Crane says.

Of course, when it comes to fuel economy, driver behavior matters, too. The difference in fuel use between an aggressive, lead-footed driver and an even-keeled, conservative one can be as much as 20 percent. To some extent, technology could nudge drivers away from their more wasteful tendencies. While autonomous driving is unlikely to result in driverless cars, at least not any time soon, the chief executive of Renault-Nissan, Carlos Ghosn, said at a recent event at Stanford University, “you’re going to see a lot of cars with less input from the driver.” Those cars can be optimized for fuel economy and efficient routing.

In the more distant future, intersections could be places where cars are programmed to slow down and weave their way through, rather than slamming the brakes or navigating roundabouts, UMTRI’s Schoettle suggests. “If no one is stopping, you’ve improved fuel economy,” he notes.

“It would be great if there was some magic bullet,” says Toyota’s Reinert—some technology that could turn a dirty car clean without us ever noticing a difference in performance, choice, convenience or pricing. The reality is multiple technologies in the right combinations can go a long way toward cleaning up our vehicles. “All these things are little,” Reinert says, “but it all adds up.”


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