Full-size SUVs are either the best or worst candidates for hybrid technology, depending on how you look at it. The 2009 Chevrolet Tahoe Hybrid is a full-size SUV that manages a noteworthy feat: It delivers fuel economy in the 20s, thanks to the technology of General Motors' first full hybrid system. Although there have been other, "mild" GM hybrids, those models required both the electric motor and gas engine to run. The "two-mode" system on the Tahoe Hybrid (and its sibling, the GMC Yukon Hybrid), however, is engineered to allow the electric motor to power the vehicle independently of the gas engine -- provided the vehicle's weight, driver's technique and terrain all fall within the limits of the electric power plant. When the driving gets more demanding, the gas engine kicks in. Essentially, the two-mode system does its most efficient work while driving around town or in stop-and-go traffic, but also affords the flexibility to deliver plenty of power when needed.

The gasoline part of this hybrid is handled by a beefy 6.0-liter V8 with cylinder-deactivation technology for enhanced fuel economy; it essentially turns a V8 into a V4 when full power isn't needed. On the electric side, there are two 60-kilowatt motors packaged inside a specialized transmission. When load conditions are light, the transmission operates as a continuously variable transmission. For heavier loads, it uses a fixed-ratio system that offers four fixed gear ratios. Like most hybrids, the Tahoe delivers city mileage that's on par with that seen on the highway. It pulls this off thanks to its ability to accelerate up to about 25 mph on electric power alone.

The gains in fuel economy above a regular Tahoe are pretty impressive from a percentage standpoint -- the hybrid posts an improvement in city mileage of up to about 50 percent (which is also better than most large crossovers). However, not all people who would need an SUV would necessarily be able to drive it in a way that would maximize fuel efficiency. Heavy loads, steep inclines and even heavy-footed acceleration all call on the V8 for assistance, which, logically, causes fuel economy to plummet. Another potential deterrent is the Tahoe Hybrid's mid-$50,000 price tag. Even factoring in federal tax credits, it could take up to a decade to recoup that price premium based on gas savings alone. We'll let you decide if the environmental benefits are worth the price, but how green can a 5,600-pound SUV ever really be?

If maximum towing capacity isn't a concern, you may also want to take a look at midsize crossovers like the GMC Acadia and the Buick Enclave. Both these choices offer fuel mileage and passenger capacity that are comparable to the Tahoe Hybrid's, yet cost considerably less. Still, if you rack up lots of miles on city streets and need an SUV that can haul the biggest loads, the 2009 Chevy Tahoe Hybrid shines as an appealing choice.

The 2009 Chevrolet Tahoe Hybrid is a full-size SUV available in one trim level. Standard equipment is extensive and includes 18-inch alloy wheels, Bluetooth connectivity, power-adjustable pedals, rear park assist with a rearview camera, tinted windows, power-folding heated side mirrors, tri-zone automatic climate control and a trip computer. An auto-dimming rearview mirror, remote engine start, leather upholstery, power front seats, a removable 50/50-split third-row seat, OnStar, a hybrid system display and a navigation system with real-time traffic are also standard. The Bose audio system comes with nine speakers, a CD/MP3 player, an auxiliary audio jack, two rear-seat headphone jacks and satellite radio. A sunroof and a rear-seat DVD entertainment system are the lone options.

Powering the 2009 Chevy Tahoe Hybrid is a 6.0-liter V8 engine coupled to a pair of 60-kilowatt electric motors located inside what GM calls an electrically variable transmission. Together, they produce 332 horsepower and 367 pound-feet of torque. Both rear-drive and four-wheel-drive versions are offered.

The powertrain can propel the Tahoe to speeds of up to approximately 25 mph using electricity only, while the V8's cylinder-deactivation system helps reduce fuel consumption at higher speeds. Regenerative braking replenishes the batteries by capturing energy normally lost when coming to a stop. Fuel economy is 21 mpg city/22 mpg highway and 21 combined for rear-wheel-drive Tahoe Hybrids; 4WD models get 20 mpg city/20 mpg highway -- but again, real-world fuel economy with the two-mode hybrid system depends heavily on driving style. Properly equipped, a 4WD Tahoe Hybrid can tow 6,000 pounds.

The arsenal of standard safety equipment on the Tahoe Hybrid includes traction control, stability control, OnStar, a rearview camera and full-length side curtain airbags. The SUV scored a perfect five stars in government frontal- and side-impact crash tests.

Perhaps a bit surprisingly, the 2009 Chevrolet Tahoe Hybrid invites comparisons to the Prius. It boasts the same stillness when accelerating and braking -- the end result of the electric motors taking over from the gas engine. Because of this, the cabin is silent as an Alpine peak. Transitions between gas and electric modes are seamless enough to be pretty much undetectable.

The braking feel offered by the regenerative braking system is pleasantly firm. GM claims that these brakes offer better stopping power than the conventional brakes featured on the gas-powered Tahoe. The big Chevy shows its weight when it comes to acceleration; it's not particularly quick off the line. Still, there's lots of low-end power for towing trailers and tooling around town.

In most respects, the Tahoe Hybrid's interior is identical to that of the gas-powered Tahoe. This is a good thing, since its most recent redesign left the Tahoe with a thoroughly appealing cabin. Materials are good-looking and high-quality, and build quality is impeccable. Controls are laid out in a way that makes them intuitive to use, and even the standard navigation system is a breeze to operate.

The Tahoe's standard third row enables it to accommodate up to eight passengers. The 50/50-split third-row seats don't fold flat into the floor, though; they must be removed manually. Each seat weighs more than 60 pounds, making them difficult to remove. With the third-row seats out of the picture, cargo capacity expands to a whopping 109 cubic feet with the second-row seats folded -- allowing this Tahoe to take the prize as the roomiest hybrid on the market.