How four car companies are forging ahead on fuel efficiency

With fuel prices and consumer interest in the environmental impact of automobiles rising, fuel economy is becoming a bigger part of the conversation when car shoppers head into dealerships. According to Consumer Reports chief executive James Guest, two-thirds of Americans responding to a survey reported that the next vehicle they purchased would be more efficient than their current car.

Between these changes in consumer demand and increasingly stringent government regulations on vehicle lineups, automakers are prioritizing efficiency and deepening their offerings of high-fuel-efficiency cars. Here’s a roundup of how some major marquees are approaching the miles-per-gallon challenge:

Mercedes-Benz: The luxury auto juggernaut sold diesel-powered sedans in the 1970s and '80s. But when the fuel price spike of that era subsided, so did American interest in the noisy, slow, somewhat inconvenient lifestyle that was diesel ownership at the time.

Mercedes has continued offering diesel sedans and SUVs in Europe all along because of consistently high gasoline prices there. Now it is returning to the US market with a fresh batch of much-refined diesel-burning vehicles. The new diesels are quiet, smooth, and capable of legendary longevity. The greatest challenge Mercedes faces in selling them is breaking down old stigmas of diesel inconvenience.

Chrysler: Before diving into alternative propulsion, Chrysler is looking to save fuel by streamlining – literally. Spearheading the initiative is the Dodge Dart Aero, which has a drag coefficient of just 0.285. For reference, a boxy Jeep Wrangler TJ has a coefficient of 0.58, while even a sleek Ferrari F430 is only good for 0.33. The Aero's most interesting feature is its "flapping jaws." The car's front grille opens and closes under the control of a microchip that monitors vehicle speed and engine temperature. When the engine needs cooling, the grille opens. When the grille doesn't open, the car streamlines itself by closing the aperture.

Additionally, the underbody of the Aero is covered by wind-directing panels, a feature usually only seen in high-performance and racing cars.

Land Rover/Jaguar: Two brands widely seen as among the worst in terms of fuel consumption and emissions are adding small-displacement engine variants to their most popular models. A four-cylinder engine will give the four-wheel-drive Range Rover Evoque 28 miles per gallon on the highway and 30 m.p.g. for the two-wheel-drive Jaguar XF sedan.

Both brands are working to separate the longstanding consumer mind-set that luxury cars and high-powered engines are inseparable. While they plan to continue to offer supercharged V8s for their range-topping models, the brands are embracing an extension of their lineup to include luxury-focused vehicles with more economical propulsion systems.

Nissan: The all-electric Leaf is Nissan's most dramatic statement in economical automobiles, but a lack of drama is what brand representative Craig Pike wants the real statement of the Leaf to be. He told the Monitor that Nissan wants to sell the Leaf not just to consumers enamored of the idea of alternative energy, but also to consumers simply looking for practical transportation.

While the Leaf’s headline is undeniably its unique propulsion system, it is designed to make a driver of a gas-powered car feel at home. The interior design holds back from committing to a "Jetsons" appearance, and comes with a host of comfort features like Bluetooth integration and heated seats. The car even creeps forward, with no pressure on the accelerator, when put in "drive," a feature integrated purely to emulate a conventional car.