For the first time, there’s a Denali package for the 2500HD chassis in a crew-cab, standard-bed 4x4 with interior leather that puts deluxe technology such as mobile WiFi, USB connectivity, Bluetooth, XM Satellite Radio, OnStar 9.0 and navigation in front of 15,600 pounds of towing capacity. General Motors says the new 397 horsepower Duramax diesel is 11 percent more fuel efficient than its predecessor. Boxed-steel frames and burly new suspensions push maximum towing capacity of the Sierra 3500HD to 20,000 pounds, and 13 of 22 2500HD models can handle payloads greater than 3,100 pounds.
