Scratch most of what you know about hybrids. Before the arrival of the Chevrolet Tahoe and the GMC Yukon, they were for tree huggers and ill-suited for towing duty. The game-changer is a new hybrid powertrain GM calls Two Mode. To check out Two Mode, I hitched the Chevy Tahoe Hybrid to a 5,320-pound three-axle box trailer.
Two Mode marries a muscular, 6.0-liter V-8 engine to a pair of 80-hp AC motors, packed inside what looks like an automatic transmission. Three planetary gear sets, regulated by four clutch packs, deliver the amalgamated power to the wheels, using four fixed ratios and two continuously variable ranges. A 300-volt battery pack stashed under the middle-row bench seat energizes the motors. Although it may be the most complex powertrain ever produced, Two Mode is seamless in operation.
When you accelerate, the engine revs normally and the motors silently heave-ho. Thanks to a number of weight-saving measures, the new Tahoe Hybrid leaves the same 5,900-pound pavement dents as a conventional 5.3-liter V-8 Tahoe.
Hauling the trailer to a 60-mph cruise required 17.2 seconds, a solid performance for any large pickup or SUV. The only sag in the acceleration curve is a momentary hesitation when Two Mode switches from low to high range at 43 mph. Following long, hard pulls, there's a hint of burned-cookie aroma in the vicinity of the battery box, but there's no other evidence of the electricity at work.
Two Mode is an apt name for this system for one unintended reason. When there's a heavy load attached, the mileage is single-digit -- in this case 7 mpg -- as you'd expect of any big truck powered by a powerful gasoline engine. But when you're motoring around in grocery-getting or commuting mode with nothing hitched to the rear, this Tahoe is capable of 20 or more mpg in both city and highway driving. The cake-and-eat benefit is 40 percent better around-town gas mileage with minimal loss of towing ability. As the Tahoe proves, hybrids aren't just for environmentalists anymore.
Chevrolet Tahoe Hybrid
• Engine 6.0-liter V-8 • Net hp@rpm 332@5100 • Net torque (lb-ft@rpm) 367@4100 • Transmission automatic with 4 fixed ratios and 2 variable ranges • Front suspension control arms, coil springs • Rear suspension rigid axle, coil springs • Brakes (front/rear) disc/disc, ABS standard • Tires Bridgestone Dueler H/L P265/65SR-18 • Wheelbase (in.)116.0 • Length (in.) 202.0 • Width (in.) 79.0 • Height (in.) 77.0 • Curb weight (lbs.) 5900 • Towing capacity (lbs.) 6,000 • Cargo volume (min/max cu.ft.) 16.9/108.9 • Fuel capacity (gal.) 24.5 • 0-60mph acceleration (w/o/w/ 5,320-lb. towed load, sec.) 8.6/17.2 • 30-60mph passing (w/o/w/ 5,320-lb. towed load, sec.) 6.3/13.3/9.9 • 60-0mph stopping distance (w/o/w/5,320-lb. towed load, ft.) 140/224 • Observed towing fuel economy (mpg avg.) 7 • Price (as tested) $53,295
LAST WORD. Chevy's Tahoe Hybrid is the first tow vehicle that both you and tree huggers will love.