General Motors announced that it is releasing new, more fuel-efficient versions of its full-size pickup trucks and SUVs.

The new XFE versions -- Xtra Fuel Economy -- will boost the miles per gallon from 14 mpg in the city and 20 mpg on the highway to 15 and 21, respectively.

"We are pulling out all the stops to deliver a more efficient package for customers who need the capability of full-size pickups and SUVs and want the very best fuel economy," said Gary White, GM North America vice president and vehicle line executive for full-size trucks. "Our pickups and SUVs are already the fuel economy leaders of their respective segments, but our engineers knew greater efficiency was achievable. We fast-tracked the XFE models to get them into dealer showrooms as quickly as possible."

GM said the XFE versions of the 2009 Chevy Silverado, Chevy Tahoe, GMC Sierra and GMC Yukon will be released. The increase in fuel efficiency comes from a combination of mechanical, aerodynamic and mass-reducing enhancements, the automaker said.

All models carry the XFE name badge and are offered in the LT trim for Silverado and LS and LT trims for Tahoe. Sierra XFE comes with SLE trim and Yukon XFE is offered with SLE and SLT trim. Most regular-production options for all models are available. Silverado XFE and Sierra XFE are offered in 2-wheel drive crew cab body styles only. Production begins this fall.

White said that Silverado and Sierra hybrids will be available in the first half of 2009. The Tahoe and Yukon models are already available as hybrids.