General Motors Co. is realizing impressive growth in the commercial segment of its business. In August, the OEM experienced an 18% increase in truck sales compared to one year earlier, including a 13% rise in Chevrolet Silverado deliveries and 10% sales growth for the GMC Sierra product line. Additionally, deliveries of Chevrolet Express vans had risen 23% and GMC Savana van units were being purchased at a rate 70% higher than the same month in 2013.
Around the same time, the manufacturer made two truck models available to Fleet Equipment for test drives. The Chevrolet Silverado test driven was the 7,200-lb. GVW High Country 4WD Crew Cab version equipped with the optional EcoTec3 6.2-liter V8 engine that is SAE-certified at 420 HP and 460 lb./ft. of torque. The standard engine for the Chevy pickup line is an EcoTec3 5.3-liter V8 rated at 355 HP and 383 lb./ft. of torque. Both engines feature direct fuel injection and continuously variable valve timing, and both switch to four-cylinder mode to save fuel during light-load driving conditions.
Driving the Silverado comfortably and safely proved easier because each engine in the model line is matched with a six-speed automatic transmission featuring auto grade braking, which downshifts the transmission on downgrades, a feature that also helps reduce brake wear. The truck also has electric power steering, which helps save fuel by cutting down on parasitic loads. Other Silverado specs for commercial operations include larger rear axles to accommodate higher engine outputs, a standard auto locking rear differential with a 3.42 ratio, trailer sway control along, and a fully boxed frame to maximize hauling capability.
The GMC Sierra test driven was a 2500HD model powered by a B20 biodiesel capable 6.6-liter Duramax turbo diesel rated at 397 HP at 3,000 RPM and 765 lb./ft. of torque at 1,600 RPM. The diesel has a range of about 5,000 miles between DEF refills and about 700 miles between diesel particulate filter regenerations, a 75% improvement over the previous system. The Duramax in the 2500HD was mated to an Allison 1000 six-speed automatic transmission with tap up/tap down shifting. Features include a tow/haul mode that reduces shift cycling, trailer sway and integrated trailer brake controls, hill start assist, automatic grade braking, intelligent brake assist and an exhaust brake.
With the Duramax diesel, the standard 36-gal. fuel tank enabled up to 680 miles between fuel stops. The Sierra 2500HD’s standard powertrain is a 360-HP, 380-lb./ft. Vortec 6.0-liter gas V8 and a Hydra-Matic six-speed automatic transmission. New starting with 2014 crew cab 2500HD models is an option for bi-fuel compressed natural gas and bi-fuel-compatible versions of the engine.
The Sierra 2500HD sports a maximum payload capacity of 4,212 lbs., conventional towing capability of 13,000 lbs. and a maximum fifth wheel towing capacity of 17,800 lbs. Sierra HD models are offered in 18 different fully boxed frame assemblies to accommodate a variety of applications. Front gross axle weight ratings up to 6,000 lbs. are available so snowplows can be fitted on 4WD configurations. Five torsion bar rates support different front gross axle weight ratings in the model lineup to help stabilize the range of heights of various models under load.
For 2015, GM has announced that Chevrolet Silverado and GMC Sierra light-duty pickups will maintain a 12,000-lb. maximum available trailer weight rating as they transition to new ratings based on SAE J2807 performance requirements for GCWR and trailer weight ratings. Additionally, the new GM-developed Hydra-Matic eight-speed automatic transmission will be standard on models equipped with the 6.2-liter EcoTec3 V8. The eight-speed is approximately the same size and weight as the Hydra-Matic six-speed automatic but its 7.0 overall gear ratio spread is wider. Providing a numerically higher first gear ratio helps with heavy loads and numerically lower rear axle ratios reduce engine RPM at highway speed. For more information, visit GM Fleet & Commercial at www.gmfleet.com.
