NEW LOOKS and interior refinements make the all-new GMC Sierra Heavy Dutys serious contenders for our Truck of the Year competition—and they feature the most powerful diesels in this class.
All HDs come standard with a 6.0-liter gasoline V-8 putting out 353 horsepower and 373 pound-feet of torque mated to a Hydra-Matic 6L90 six-speed automatic. The 6L90 has a 6.04:1 overall ratio spread with two overdrive gears helping the HD’s performance and fuel economy, but the cleaner, more powerful Duramax 6.6-liter turbodiesel engine is the real story. With the biggest numbers in the field, the Duramax puts out 365 horsepower and a massive 660 pound-feet of torque. A new particle-trap system helps provide a 90-percent reduction in exhaust particulates and a 50-percent reduction in NOX to meet the new mandates set…
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MotorTrend (Digital) - 1 Issue, February 2008