General Motors' previous fleet of full-size SUVs had environmentalists cowering behind the redwoods. The unsophisticated, clunky old SUVs chugged gasoline. But the new generation, including the Chevrolet Tahoe, represents a huge improvement in technology, comfort, handling, and environmental awareness, even if the vehicles still weigh a ton—actually, they weigh closer to three.

I tested a 2007 Chevy Tahoe loaded with techno goodies and options typical of what you'd find in the upper reaches of the GM line. This line comprises full-size SUVS: the Tahoe, GMC Yukon, and Cadillac Escalade, and the jumbo-size vehicles that stretch 20 inches longer, up to 222 inches: the Chevy Suburban, GMC Yukon XL, and Cadillac Escalade ESV. The new Tahoe is a little heavier and bulkier than previous versions, but for a vehicle that weighs just less than 6,000 pounds, its handling is more precise and car-like.

GM put in a mega-order for SUV microprocessors, and it uses the chips to good effect: It has improved the vehicles' anti-lock braking systems and now offers computer-aided stability control, roll-over mitigation, and tire-pressure monitoring as standard features. Given how affordable stability control can be (on a $35,000-minimum vehicle) and how foolish new-to-the-fold SUV drivers can be, GM was a bit late in making stability control standard.

You no longer feel like you're in a thinly disguised truck, thanks to improved fit and finish; major leaps in safety, emissions, and fuel economy; and the contemporary feeling to the cockpit. But don't drive this Shamu-like vehicle to the autocross instead of your Subaru WRX or Mini Cooper; a truck that handles well is still a truck. At least you no longer have to worry that a sudden swerve might put you upside-down in a ditch, checking out OnStar Mayday assistance, which is free for the first year. Continued...

Flex-Fuel Engines

The Tahoe and many other GM cars, including the new SUVs, run on either gasoline or E85, a fuel made of 15 percent gasoline and 85 percent ethanol (a grain alcohol typically made from corn). E85 is touted as a clean-air, low-petroleum fuel. Your gas mileage will suffer with E85, though, because it contains only two-thirds as much energy as normal gasoline. But the fuel can be compressed more in the engine before ignition, so you end up losing only about 5 to 15 percent in fuel economy.

So if your mileage falls 10 percent, E85 needs to cost roughly 10 percent less ($2.25 instead of $2.50 a gallon) for you to come out even, leaving aside the cleaner-air, stick-it-to-the-OPEC-cartel, and support-American-farmers aspects of E85. Some scientists say the energy spent converting a grain biomass to ethanol makes ethanol a net loser. I'm not taking sides yet; I'm just noting that not everyone finds ethanol an environmental panacea.

Running on gasoline, the four-wheel-drive Tahoe returns 15 mpg in the city and 21 mph on the highway, according to EPA testing. In the real world, you've got a fighting chance of seeing 20 mpg on long highway trips, which isn't bad for a 5,607-pound vehicle. One technology that makes 20 mpg possible is, in GM terminology, active fuel management, also called variable displacement, displacement on demand, multi displacement, and variable cylinder deactivation:: When the Tahoe is not under load, four of its eight cylinders are idled.

The Tahoe's economy and performance might have been better had Chevrolet opted for something more advanced than the four-speed automatic it coupled with the 5.3-liter, 320-hp engine. The Cadillac Escalade, for instance, gets a six-speed (to go with the seven areas of chrome highlighting on the exterior). In the Tahoe's favor, the wind-tunnel design is as aerodynamic as a previous-generation Chevrolet Corvette, GM says.

Technology and Entertainment Options

Chevrolet offers a navigation system for $2,145. That's a lot for any nav system, but it's especially high because this system is not the best. You'd be better off waiting for the OnStar Turn-by-Turn system, which will come with the later 2007 model. Turn-by-Turn offers a live OnStar operator who will key in your destination and send audio navigation instructions and a trip map to your car, all for about $25 per month ($15 for basic OnStar, $10 for Turn-by-Turn, and both are free for the first year). But you don't get a moving map—only voice prompts and a one- or two-line text prompt in the driver information panel. Note that if you buy the LCD nav system now, Turn-by-Turn will not be able to download directions to it.

Each of the five Tahoe models has a line-in jack and can play MP3 CDs, and all except the base-model LS allow two entertainment streams; the rear one has a separate volume control and headphone jacks.

Chevy has other option-availability quirks that arise from trying too hard to segment one vehicle into five sublevels. You can get audio controls on the steering wheel in every model but the LS. Steering-wheel audio control as an option might make sense on an econobox, but when a vehicle costs as much as the average family earns in a year, it should be standard on all models. That said, the buttons are big and easy to press.

Back-seat entertainment, a must for a kid-carrying vehicle, costs $1,245—not a bad price. You can add more speakers or upgrade to a Bose audio system by choosing different audio packages. XM Satellite Radio is a $199 option, which is affordable compared with the $5,00-plus that some carmakers charge. A small driver-information panel provides short messages, trip computer readouts, and car data not provided by the gauges. You can get only one piece of information at a time. This info panel will likely provide the OnStar Turn-by-Turn prompts in 2007. Continued...

Beyond Tech: Other Observations

I was impressed by the interior design and fit and finish. The cockpit looks contemporary, and the leather feels more like leather this time around. Everything fits. Squeaks and rattles are noticeably absent.

But the lumbar support on the high-end LTZ seats didn't do much for my back. The climate controls were a bit fussy, didn't take advantage of the LCD panel in nav-equipped models, and seemed designed more for looks than for functionality. And the gearshift lever remains massive, whereas the LCD is small, mounted low, and difficult to read on sunny days.

Second-row seating is comfortable, but the third row is best for middle-schoolers and jockeys. You can add power-release middle seats that flip forward and out of the way, but you have to reposition them manually, and the feature is available only on some models (of course).

Why SUVs Matter to GM

The full-size SUV is GM's Maginot Line for profits: If they go away, GM, like the French, can raise the white flag. GM accounts for about 60 percent of the approximately 750,000 full-size SUVs sold in the United States in recent years, and the margins can be spectacular when buyers tack on options and pay close to list price.

Online: Service Information

Browsing Chevrolet's Web site can be a hassle, because of the dozens of interlocking options. Some options show up with a price of $0, but it's unclear whether that means they are included as standard features or just unavailable. Other options boxes can't be checked, and no prompt explains why. Several times while configuring a vehicle, I clicked the Next button, and the options I had just chosen didn't carry over to the next screen, forcing me to begin again. But even so, I'm sure that Chevy's Web site can tell you which configurations are available more accurately than a sales rep at the dealership can.

The owner area of the GM's Web site, mygmlink.com, will automatically populate your personal owner's page with details of service work done by GM dealers. Few (if any) other automakers' sites do that. But it's frustrating that you can't register your new vehicle online for 60 days after purchase and that information wasn't yet posted for early 2007 models such as the Tahoe.

Should You Buy?

If you need a full-size SUV with three rows of seats, the GM lineup is where you should start and perhaps end your search. The Tahoe, Yukon, Suburban, and Escalade all really are much better vehicles than their predecessors. If you'll be pulling a boat or trailer, they really make sense. Some models can be configured to seat as many as nine passengers, with three rows of bench seats. If you want to haul three rows of passengers and their luggage, then you'll need the longer Suburban, Yukon XL, or Escalade ESV. Just know that they'll be a handful to park and maneuver.

Within the Tahoe line, I'd pass on the base LS model, because it doesn't offer some useful technology options. I would chart a course to the middle of the LT line, the LT2, which includes wheel-mounted audio control and bucket seats (options that come on the LT1), plus leather seating, a six-disc CD changer, power adjustable pedals, remote vehicle starting, and rear-parking assist, at $40,580. Then add the Bose audio system ($495), XM radio ($199), side air curtains ($350), rear entertainment system ($1,295), and probably the nav system ($2,145), which allows you to add the backup camera ($195), for a total list price of $45,624.

The one useful step-up feature in the LT3 version is the power folding outside mirrors. Without folding them in, your mirrors would probably scrape both sides of a standard 8-foot garage door. The sporty LTZ version can cost up to around $51,000, or 40 percent more than an entry-level Tahoe. (An Escalade can run into the sixties). Tahoe buyers probably want the peace of mind that four-wheel drive affords, but you pocket $2,200 and gain 1 mpg city and highway with rear-drive only.

Is the Tahoe right for you? If you like riding up high, if you feel more secure in a heavy vehicle, or if you're towing, then check out Tahoe. And if you want to carry a lot of people and cargo, check out the bigger Chevy Suburban.

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$35,000 to $51,000; TechnoRide-recommended configuration, $45,624.

GM's new full-size SUVs offer better fuel economy for such large vehicles (15 mpg city, 21 mpg highway), vastly better ride and handling, and more technology. Half the V8's cylinders shut down when not you're accelerating, and stability control comes standard. The $2,145 navigation system is decent, and the $1,295 rear-seat DVD system is a must-have for families.

Stability control and OnStar are standard. Decent nav system. Cylinder-deactivation feature. Runs on E85, an ethanol/gas mix. Backup camera and sonar available.

No Bluetooth. Unsophisticated transmission. EPA rating is 15/21 mpg (city/highway). Less room than most minivans.