Cadillac launches jumbo hybrid Escalade SUV

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By Herb Shuldiner MOTOR MATTERS

Don't send in the pallbearers for full-sized sport utility vehicles — at least not yet. Cadillac introduces a new wrinkle in jumbo SUVs, a three-ton hybrid Escalade with a surprising fuel-efficient performance of 21 miles per gallon on the highway. In city driving, the hybrid Escalade delivers 20 mpg, a 50 improvement over the conventional model. That's pretty spectacular for a vehicle that tips the scale at more than 6,000 pounds and could help prolong the existence of this class of vehicle.

The new two-mode hybrid system was developed by GM in a joint venture with Mercedes-Benz and BMW. GM already has introduced the two-mode system in the Chevy Tahoe and GMC Yukon. Chrysler will use the two-mode hybrid system in the Dodge Durango and Chrysler Aspen. BMW is expected to include the innovative hybrid system in the SUVs it builds in its South Carolina plant. Mercedes-Benz will also use the system in its Alabama-built SUVs.

Note that all the applications built so far, or planned for the near future are SUVs. That's because the two-mode hybrid system was designed to boost fuel economy in vehicles that are conventionally known to be gas-guzzlers, which are no longer acceptable in this era of skyrocketing fuel prices. The fuel efficiency of the 2009 Escalade is astonishing for a vehicle of this size, weight, eight-passenger capacity and 5,600-pound towing rating (AWD model).

The new hybrid system enables a driver to launch the Escalade on electric power and drive at low speeds solely on electricity. As the big SUV picks up speed, its 6.0-liter V-8 takes over for higher speeds. Like other hybrid systems, the engine shuts down when you're stopped at red lights to lessen fuel consumption. The 332-horsepower V-8 also stays shut down when in heavy traffic and at slow moving speeds. Only electric power is used in these conditions to further increase fuel economy and lower emissions.

An additional fuel-saving innovation on the 2009 Escalade is GM's Active Fuel Management system. AFM shuts off half its cylinders when the vehicle is cruising down the highway at steady speed and less power is required to move the Escalade. Key components of the two-mode hybrid system include an electrically variable transmission and a 300-volt nickel-metal hydride battery pack. It also has two electric motors that can drive the hybrid on electricity alone, or in combination with the V-8 when half of its cylinders shut down.

This not only helps fuel economy, but also additionally reduces environmentally damaging emissions. A bonus of this mode is that highway fuel economy increases by 25 percent. The battery pack is located under the second-row seats. This requires no extra space and does not interfere with getting into the second- or third-row seats. The nickel-metal hydride cells not only power the electric motors, but also the electric power steering system and the air conditioning compressor. Power created by regenerative braking is used to recharge the battery pack.

The regenerative brakes work along with standard hydraulic brakes to stop the three-ton Escalade. If only a small amount of braking force is required to stop the vehicle, then the hydraulic brakes may not even be required. This results in less wear on the hydraulic braking system, but if required to stop quickly you get the benefit of stopping with both braking systems.

There's no hint yet what it would cost to replace the battery pack, but the new hybrid Escalade comes with an eight-year or 100,000-mile warranty.

Cadillac's general manager, Jim Taylor, predicts that about 3,500 of the two-mode hybrid Escalades will be available this year. Pricing has yet to be announced.

Some critics complain that even with its increased fuel economy the hybrid Escalade remains a symbol of fuel waste. But not everyone's transportation needs can be met by a subcompact.

There is a legitimate need for vehicles that can carry eight occupants, a considerable amount of cargo or tow horse trailers, recreational vehicles and big boats.

The hybrid Escalade permits this and makes a small contribution to progress in fuel economy.