GM's Two Mode hybrid also features a cylinder deactivation system.
By RICHARD TRUETT AND LESLIE J. ALLEN | AUTOMOTIVE NEWS


The hybrid versions of the full-sized 2008 Chevrolet Tahoe and GMC Yukon SUVs will deliver fuel economy gains of 50 percent in the city over the standard, non-hybrid models.

Today (Sept. 27, 2007) at the Texas State Fair, General Motors will announce the EPA fuel economy estimates of 21 mpg city and 22 mpg highway for the two-wheel drive versions of the Tahoe and Yukon hybrids.

Those fuel economy ratings are expected to give GM best-in-class fuel economy for large SUVs. The ratings also rival those of many midsize and large cars. For example, the 2WD Tahoe and Yukon match the four-cylinder Toyota Camry's 21 mpg city rating and beat the V-6 Camry's city rating by 2 mpg.

GM expects to sell 10,000 units per year, combined, of the hybrid SUVs. Prices won't be announced until closer to launch, but are expected to start in the low- to mid-$40,000 range.

The Tahoe and Yukon hybrids are the first vehicles to use the innovative Two Mode hybrid transmission GM developed with DaimlerChrysler and BMW. GM will also use the hybrid system in pickup trucks.

The EPA fuel economy figures are lower than some expected, but that's due to the agency's changing its test procedures to more accurately reflect real-world driving conditions.

The official EPA figures for both vehicles are 21 city/22 highway for 2WD models and 20 mpg city/20 mpg highway for 4WD models.

The Yukon and Tahoe hybrids are equipped with GM's cylinder deactivation system, which cuts off four of the V-8's cylinders when the vehicle reaches highway cruising speeds. They have lightweight body panels and wind-cheating bumper covers.


The 2008 Yukon Hybrid goes on sale in early November.
The two-mode hybrid is a full hybrid, meaning the Tahoe and Yukon can drive entirely on electricity. GM's two-mode hybrids can go up to 32 miles per hour using just electricity. At higher speeds, the two-mode system uses either all gasoline or a combination of fuel and electric propulsion.

GM, DaimlerChrysler and BMW invested $1 billion in the Two Mode system.

"This is something that really changes the game," said Gary White, GM vice president and vehicle line executive for full-sized vehicle development team.

Tahoe and Yukon hybrids are by far the most fuel-efficient large SUVs on the market. By comparison, the two-wheel drive 2008 Nissan Armada and Infiniti QX56 and the two-wheel drive Ford Expedition all get EPA ratings of 12 city and 18 highway. The EPA has not released figures for the 2008 Toyota Sequoia.

The Nissan and Infiniti ratings are for the 5.6-liter V-8 and the Expedition rating is for the 5.4-liter V-8. GM's Two Mode hybrid SUVs have a 6.0-liter V-8 engine.

GM is also planning to use the Two Mode system in its Silverado and Sierra pickups. The Dodge Durango will use the Two Mode system next year, and Mercedes-Benz and BMW will use their versions in the ML 450 and X6 SUVs.


Two Mode Specifications
The 2008 Chevrolet Tahoe Hybrid and GMC Yukon Hybrid tow like SUVs, but are no more thirsty than a midsized car.

Price: Low-to-mid $40,000 range

City/Highway EPA Ratings: 21/22 (two-wheel drive); 20/20 (four-wheel drive)

Engine: 6.0-liter, V-8

Horsepower: 332 hp

Torque: 367 pounds-feet

Transmission: Two Mode hybrid/four speed automatic

Batteries: 300-volt nickel-metal hydride for hybrid system; 12 volt for accessories

Towing capacity: 6,200 pounds (2WD); 6,000 pounds (4WD)

Curb weight: 5,541 (2WD); 5,787 (4WD)

1. How is GM gonna have more hybrids on the road than Lexus and Toyota within a year? Yeah right.

2. 0-30 only electric power? Not according to what I read on their website. If you accelerate slowly enough I suppose.

3. 322 hp delievered from 2 electric motors without the help of the gasoline engine? Are you joking? That would depelete the batteries so fast.