2015 GMC Sierra Denali

By Tom Crosby

General Motors has been selling trucks for more than 110 years and their best seller is the Sierra pickup with more than 150 possible configurations for customer customization.

This year the heavy-duty (HD) versions – the 2500 and 3500 – were restyled and upgraded inside and out with more comfort features while retaining their competitive ruggedness and towing power.

Our test drive was the top of the line (above base, SLE and SLT) Sierra Denali 2500 4-wheel drive crew cab with the shorter (6.6 feet) truck bed.

Powered by an optional 6.6-liter, cast-iron, turbo-charged diesel engine with a six-speed Allison transmission, mileage roughly ranged between 15-mpg city and 19 mpg on the highway.

The 2500, which only comes as a crew cab, is not mileage rated by EPA due to its weight.

Its Duramax engine was designed to operate under a rough-duty cycle for 200,000 miles without a major overhaul, aided greatly by 765-ft-lbs of torque at low rpms.

That means buyers can expect the 2500 to hold a high resale value, even after towing frequently with a fifthwheell/gooseneck hitch GM says can pull 17,100 lbs. with trailer sway control.

An exhaust braking system reduces brake wear by controlling speed when descending a hill. Behind the wheel, power is ample, the ride properly truck-cushioned by a torsion bar front suspension and a two-stage leaf spring in the rear.

Safety options included warnings for blind spots, collisions and lane departures – helpful when driving a 20-foot long, 3.5-ton truck. With other options, including 20-inch all-terrain blackwall tires – the final price tag was $64,575 after a $1,500 discount.

While pricey, the workhorse nature of the 2500 was nicely offset with the upscale interior, with its white contrasting stitching, aluminum trim, comfortable leather seats and versatile 8-inch screen and dashboard controls.

Twin instrument gauges are 3-D with a colored info screen between. The navigation screen, using Interlink and its natural voice feature, was responsive with amply timed turning warnings. Knick-knack spaces and plug-ins are plentiful and available music apps, like Pandora, use a clear-sounding Bose audio system.

Outside, a bigger honeycomb grille, body-color bumpers and power-dome hood identify it as a muscular 2015 model. There is a rear bumper step-up to the hydroform truck bed, and four metal loops that can be inserted on the sides for needed tie-downs. Ground clearance overall is 8.4 inches and step-in is 26 inches with a 17-inch high running board.

LIKES: Mileage, ride, interior comfort, versatility, handling
BOTTOM LINE: Size counts in pick-ups but 2500 also oozes nice inside luxury.


  • Base price w/destination fee$54,835
  • Curb weight 6,525 lbs.
  • Wheelbase153.7 inches
  • Length239.5 inches
  • Width80.5 inches
  • Engine specs6.6-liter, V-8, turbo diesel (option)
  • Horsepower397-hp at 3,000 rpm
  • Torque765 lbs.-ft. at 1,600 rpm
  • Transmission6-speed HD Allison automatic
  • Test drive mpg rating17.3 mpg, mostly highway
  • Range36-gallon tank, diesel
  • Performance0-60 in under 8 seconds