-- or extra fuel economy -- versions of the 2009 Chevrolet Silverado and GMC Sierra trucks and Chevrolet Tahoe and GMC Yukon SUVs will get one mile per gallon more in both city and highway fuel economy than non-XFE versions. The boost will give them a total of 15 miles per gallon in the city and 21 on the highway.
On XFE models, GM improved the aerodynamics by extending the front lower air dam, lowering the suspension and revising the chassis tuning. The automaker also reduced the mass with aluminum parts, including an aluminum spare wheel and 17-inch aluminum wheels, gave the vehicles low rolling resistance tires and powered them with a 5.3-liter, ethanol-capable V-8 engine that has an aluminum cylinder block and heads.
GM stressed that the vehicles still have the same towing capability.
The XFE pickups and SUVs will be available in the fourth quarter of this year. GM spokesman Brian Goebel wouldn't say how much more they will cost than non-XFE versions.
GM began offering an XFE version of its Chevrolet Cobalt small car earlier this year. The automaker said it sped development of the XFE trucks and SUVs because of consumer demand for more fuel-efficient vehicles. GM's truck and SUV sales fell 23 percent in the first seven months of this year.
GM also offers hybrid versions of the Tahoe and Yukon and plans to bring out hybrid versions of the Silverado and Sierra in the first half of 2009. The company said last week that about 4 percent of its Tahoe and Yukon sales have been hybrids so far this year.