Driven

BY JIM GORZELANY

FUEL’S FUTURE

These fuel-saving systems will help boost the mileage of tomorrow’s cars.

Automakers are working overtime to boost their fleets’ fuel economy while avoiding the wholesale downsizing that rocked the industry in the 1980s. To that end, engineers are implementing an array of technologies to help wring every last mile out of a gallon of gasoline for tomorrow’s models. Here’s a quick glance at five technologies you’ll see in increasingly widespread use down the road.

Hybrid Power

Gaining steadily in popularity, higher-mileage hybrids employ an electric motor/generator and a self-charging battery pack to help share the load with a conventional gasoline engine. The Toyota Prius hybrid is a legendary gas-sipper, rated at 48 mpg in the city and 45 on the open road. For 2008, the technology will carry over to what are otherwise among the least-efficient models on the road: hybrid versions of the full-size Chevrolet Tahoe, Chrysler Aspen, Dodge Durango and GMC Yukon SUVs. Each will realize about a 25% gain in fuel economy. They’ll be followed in 2009 by hybrid Cadillac Escalade, Saturn VUE SUVs, Chevrolet Silverado and GMC Sierra pickups.

Plug-In Hybrids

Coming soon will be hybrids that pack larger batteries and can run solely on electric power for an extended period of time, provided they’re tethered to an electrical outlet each night for recharging. A plug-in hybrid Saturn VUE is expected by 2010 that will go for 20 miles per charge on battery power alone, which is roughly the average American’s daily commute. What’s more, the Chevrolet Volt sedan, planned for 2010 or 2011, will run solely on electricity, using a small gasoline engine to operate a generator when the plug-in, rechargeable battery is depleted.

Variable Displacement

A few V8-powered models can now shut down half of their engines’ cylinders when not needed—typically at cruising speeds—to realize about a 10% boost in fuel economy. Expect variable displacement to become relatively commonplace in the future. The 2008 Honda Accord is the first vehicle to apply it to a V-6 engine; it can run on three, four or all six cylinders as needed.

Automatic Shut-Down

This technology automatically de-powers a vehicle’s engine at idle and restarts it in a flash when the accelerator is depressed. This typically saves about 10% fuel consumption in city driving. Already employed in hybrid vehicles, General Motors offers this system in the Saturn Aura and Chevrolet Malibu, and BMW has announced that it will soon implement it in future models.

Diesel Power

Diesel-fuel engines typically boast 20% to 25% greater fuel economy over comparable gasoline power plants, with strong acceleration. Unfortunately, current diesels from Mercedes-Benz and other automakers can’t be sold in eight states that adhere to the strictest emissions standards. However, a coming generation of “cleaner” diesel engines should be 50-state compliant and will take to the streets in cars and trucks beginning in 2009.