Fuel efficiency standards will change the way autos look

David Cooper | Toronto Star | Getty Images

Toyota Prius Plug-in Hybrid.

Forthcoming fuel-efficiency standards may do more than ease drivers' pain at the pump. They could result in a dramatically different look for your next new car.

Under the corporate average fuel economy (aka CAFE) standards approved last August, automakers' 2,025 fleets must average 54.5 miles per gallon—which would make them nearly twice as fuel efficient as currently required. Those standards and other previously approved rules mandate smaller improvements in the interim.

Increasing fuel efficiency so substantially requires automakers to get more creative than simply introducing more hybrid or electric models. Design experts say future models could include lighter materials, more aerodynamic shapes or more powerful engines. Or all of the above.

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"You've got one goal, to increase efficiency, and a variety of ways to get there. It's usually not just one thing," said Jason Hill, president of vehicle design studio Eleven and an instructor of transportation design at the Art Center College of Design in Pasadena, Calif.

Some of the changes drivers might encounter:

Performance components. Many of the biggest changes have been under the hood. Automakers are continuing to experiment with engines that use alternate fuels, but there are also more powerful gas engines and power trains that greatly improve fuel efficiency, said Jack Nerad, executive editorial director for Kelley Blue Book.

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Many of the new engines are also smaller and lighter, further improving efficiency. Smaller components also free up designers to change the shape of a vehicle—such as by lowering the hood, said John O'Dell, a senior editor for Edmunds.com.

Materials. "Much like aircraft, with cars, lighter is always better," said John Manoogian II, founder of vehicle design studio Forzablitz and a visiting professor of vehicle design at the College for Creative Studies in Detroit. Drivers could see more cars, or pieces of them, made from alternate materials that are strong but less weighty, such as carbon-fiber composites.

Technology. The shift from interior buttons and knobs to touchscreens or windshield displays contributes to lighter-weight vehicles, Hill said. There are fewer components needed, and it results in a more streamlined vehicle interior.

Of course, smarter cars also enable more driver education, with screens showing details about fuel efficiency on a particular trip and apps offering tips to drive more efficiently. "The potential for a trend, for that to be a cool thing to do, is there," he said.

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Vehicle aerodynamics. The Toyota Prius isn't fuel efficient solely because it's a hybrid. A significant portion of its efficiency is coming from aerodynamics, Manoogian said. Consumers are likely to see some more vehicle models that stand out, like the Prius, as automakers play with aerodynamics.

But improving a vehicle's aerodynamics can often come down to tweaks such as the size, shape and placement of mirrors and grilles. In smaller doses, those changes aren't likely to be noticeable to consumers.

And for all changes, the design evolution is likely to be slow. Next year's cars may not look substantially different, but over five to 10 years, they will look markedly different than today's, said Manoogian.

It's a challenge for designers and automakers to advance the look and improve efficiency, without making too-drastic changes that could alienate drivers.

For example, GM's electric hybrid Cadillac ELR, due out in 2014, doesn't need a grille, but designers opted to incorporate one anyway, said Manoogian, who served as director of exterior design for Cadillac. "You don't want to shock the public very much," he said.

To be sure, advancements won't come cheap. Steps taken to make cars more fuel efficient could push up purchase prices by $1,000 or more in coming years, said O'Dell.

The biggest price jumps could show up in smaller models that have already been optimized for fuel efficiency—and so may require more drastic changes than larger vehicles. "A Hummer has all the aerodynamic properties of a brick, but a few barely noticeable curves would dramatically increase its fuel efficiency," said O'Dell.

But automakers could opt to raise the price of bigger vehicles substantially, too, as a way of subsidizing pricier changes on other models.

—By CNBC.com's Kelli B. Grant. Follow her on Twitter @KelliGrant.