General Motors is building on the segment-leading fuel economy of its full-size pickups and SUVs with new XFE (eXtra Fuel Economy) versions of its 2009 Chevy Silverado, Chevy Tahoe, GMC Sierra and GMC Yukon models. Following on the success of the carmaker’s first XFE model, the Chevrolet Cobalt, which at an EPA rated 36mpg (6.5L/100km) is 10% more fuel-efficient than the standard Cobalt, GM has applied the same combination of mechanical, aerodynamic and mass-reducing enhancements to its line of full-size SUV and trucks.

The end result is a 5% increase in EPA-estimated highway fuel economy and more than 7% improved mileage in city driving.

The biggest impact is made by improvements to the aerodynamics of the vehicles. The enhancements on the Silverado XFE and Sierra XFE, for example, makes the utilities the most aerodynamic full-size pickups in the industry, with a best-in-class 0.412cd. The pickups join the Tahoe Hybrid and Yukon Hybrid as the most aerodynamic full-size SUVs at 0.349cd. A rear axle equipped with a fuel-saving 3.08 ratio is also standard on all XFE models. Lightweight aluminum wheels and low rolling resistance tires (with higher standard tire pressures) also are included on all models.

The XFE packages are available on 2WD vehicles equipped with a new 5.3L V8 engine and six-speed transmission. They achieve on average 15mpg (15.7L/100km) in the city and 21mpg (11.2L/100km) on the highway, versus the comparable non-XFE models, which rate at 14mpg (16.8L/100km) in the city and 20mpg (11.8L/100km) on the highway.

The new engine, dubbed the LC9, is built with a mass-reducing aluminum cylinder block and heads. It is rated at 320hp (238kW) and 340lb.-ft (461Nm) of torque in the Tahoe and Yukon and 315hp (235kW) and 338lb-ft (458Nm) in the Silverado and Sierra.