General Motors is the only automaker to have two new engines on Ward’s AutoWorld magazine’s 2008 "Ten Best Engines" list for North America.

The GM Powertrain engines making Ward’s 14th annual list were the Vortec 6.0L Gen IV small-block V-8 hybrid engine, which is in the all-new 2008 Chevrolet Tahoe and GMC Yukon Hybrid full-size SUVS; and the 3.6L V-6 VVT with direct injection in the 2008 Cadillac CTS, which was recently named Motor Trend’s 2008 Car of the Year. The awards will be presented on Jan. 16, 2008 at the North American International Auto Show.

"We are pleased Ward’s has recognized our commitment to improving fuel economy without compromising the performance and capability that our customers demand in their cars and trucks," said Tom Stephens, GM group vice president, GM Global Powertrain and Quality.

Vortec 6.0L Gen IV small-block V-8 hybrid

The 2008 Chevrolet Tahoe Hybrid and GMC Yukon Hybrid boast the same city fuel economy as a much-smaller, four-cylinder sedan thanks to a state-of-the-art hybrid system pairing GM Powertrain’s new, modified Vortec 6.0L small-block V-8 with its 2-Mode hybrid transmission.

GM engineers adapted the 6.0L V-8 to operate with late intake valve closing for reduced pumping losses and better overall fuel economy. The Vortec 6.0L V-8 produces 332 horsepower (248 kW) at 5100 rpm and 367 lb.-ft. of torque (498 Nm) at 4100 rpm, yet requires only regular unleaded fuel. In addition, the Vortec 6.0L engine features Active Fuel Management™, which allows four of the eight cylinders to be shut off during periods of light load.

Two-wheel-drive Tahoe and Yukon Hybrid models deliver 21 mpg in the city, a 50-percent improvement over their 5.3L non-hybrid siblings, according to EPA labeling, and the same EPA city fuel economy of the much-smaller 2008 2.4L-equipped Toyota Camry sedan.

Two GM engines on Ward's 'Ten Best Engines' list
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3.6L V-6 VVT with direct injection

GM Powertrain’s new 3.6L V-6 VVT with direct injection technology is GM’s highest output V-6 and one of the most fuel-efficient in GM’s high-feature engine family. It made its debut as the top-level engine in the new 2008 Cadillac CTS, delivering 304 horsepower (227 kW) and 273 lb.-ft. of torque (370 Nm) - a 15-percent increase in horsepower and 8-percent increase in torque.

Even with this performance, the 2008 CTS equipped with the 3.6L V-6 VVT with direct injection and automatic transmission delivers 2008 EPA fuel economy of 17 mpg city and 26 mpg highway - an improvement of 3 percent over its predecessor. The engine helps the CTS achieve 0-60 mph performance of 5.9 seconds and a top speed of 155 mph (248 kph). The engine is available with either an automatic or a manual transmission.

The 3.6L DI V-6 with direct injection engine is also available in the 2008 Cadillac STS and improves fuel economy by 1 mpg in the city and 3 mpg on the highway, while providing a 47 horsepower increase over last year’s model.

The application of direct injection reduces cold-start hydrocarbon emissions by 25 percent and it is designed to operate with regular unleaded gasoline.

Gasoline direct injection differs from the fuel delivery process of a conventional fuel injected engine by delivering fuel directly into the combustion chamber, where it is mixed with air drawn in to the chamber. The advantage is improved fuel control and a more complete burn, which generally requires less fuel than a conventionally injected engine of the same size and configuration.

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