From supersize fries to jumbo jets, lots of folks in the United States like things "big." For hundreds of thousands of new vehicle buyers, small or midsize simply doesn't cut it. They need maximum everything--from space to haul up to eight people and all their gear to towing a party boat--the only choice is a large SUV.

Around the turn of the century, large SUVs enjoyed large amounts of success in the marketplace, selling more than 1 million units annually. With $4.00/gallon gasoline not going away anytime soon, the market continues to shift away from large SUVs among casual drivers. Sales in this class are way down, with no major upturn in sight. That's not the kind of news that makes the automakers' bean counters happy, as these particular vehicles tend to be the most profitable.  

Ironically, while large SUVs are just that, the number of competitors in this segment is not. The Auto Editors of Consumer Guide classify six vehicles as large SUVs. Those players are: Chevrolet Suburban and Tahoe, Ford Expedition, GMC Yukon, Nissan Armada, and Toyota Sequoia. Domestic brands continue to dominate sales in this class.

All is largely quiet on the big SUV front for the 2009 model year. Armada is unchanged, as 2009 might very well be its final model year. All Expeditions and certain four-wheel-drive versions of the Sequoia add the ability to run on E85 ethanol-blended fuel.

General Motors' trucks, the Suburban, Tahoe, and Yukon, make news by increasing availability of a 6-speed automatic transmission. Rear-drive Tahoe and Yukon models can also be equipped as "XFE," which stands for "Xtra Fuel Economy." XFE versions have a 320-horsepower 5.3-liter V8 engine, a 6-speed automatic transmission, revised suspension components and drive ratio, and low-rolling-resistance tires. These changes promise increased fuel economy.

The 2009 Chevrolet Tahoe and GMC Yukon hybrid models are unchanged following their introduction for model-year 2008.

Under the Skin

Besides brawny styling, large SUVs derive much of their engineering from workhorse large pickup trucks. This means plenty of available power, even if the vehicle is loaded with passengers, cargo, and a trailer. They can also tackle tough terrain when asked (and properly equipped).

All the vehicles Consumer Guide classifies as large SUVs are available with rear-wheel drive or four-wheel drive. The 4WD systems on each vehicle are "full time," which means that drivers can set a switch on the dashboard to allow power to go to all four wheels in any condition. This is different than "part time" systems, where the 4WD mode should only be engaged on wet or snowy pavement.

For folks living in drier climates, a rear-drive large SUV will do just fine. It's not worth the added penalties in weight, fuel economy, and sticker price versus a 4WD model. For those living where rain reigns, snow is supreme, or off-road adventure is on-tap, 4WD becomes a needed asset.

While a traditional truck-based SUV has clear benefits for towing and off-roading, very distinct drawbacks also arise, regardless of whether a vehicle is rear drive or 4WD. Generally sloppy handling, high fuel consumption, and lofty sticker prices are common criticisms. Automakers, though, are working hard to mitigate those negatives without sacrificing any of the functionality large SUV buyers need.

With no end in sight to high fuel costs, one technology designed to help increase mileage is cylinder deactivation. Under cruising and light throttle conditions, an engine with this feature will shut off half of its cylinders. General Motors employs cylinder deactivation on certain versions of its large SUVs. Company officials say this feature can increase gas mileage by about 7 percent, depending on driving conditions.

The 2009 Chevrolet Tahoe Hybrid and GMC Yukon Hybrid operate in a similar manner to other hybrid cars and SUVs such as the Ford Escape Hybrid and Toyota Prius. Tahoe and Yukon hybrid team a 6.0-liter gasoline engine with an electric motor to produce a total of 332 horsepower. The hybrid can run exclusively on the electric motor at low speeds and switch to the gas engine at higher speeds or under heavy throttle.

EPA estimated fuel economy ratings for the hybrid are 20 mpg city/20 mpg highway for 4WD versions and 21 mpg city/22 mpg highway for the rear-drive models. A non-hybrid version with the standard 5.3-liter V8 engine is rated for 14 mpg city/20 mpg highway. GM says rear-drive XFE Tahoes and Yukons will achieve 15 city/21 highway. One drawback to the hybrids, though, is decreased towing capacity. A gas-only Tahoe can tow up to 8400 pounds, but hybrids are only rated up to 6200 pounds.

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