“The rear headrests are the biggest disappointment in the vehicle. They are a safety concern since the headrests cannot be adjusted to the proper height for the rear seat occupant. When pushed, the headrests drop to the lowest setting.”
2015 GMC Sierra 3500: What's New, Specs & Features
Last updated August 13, 2026
The 2015 GMC Sierra 3500HD is a full redesign, not a carryover. Its biggest change is an all-new body and cabin, joined by a quieter cab, a new Double Cab body style, and easier-to-use cargo-box features.
About the 2015 GMC Sierra 3500
2015-2019 Sierra HD generation, first year of the redesign.
GMC positions the Sierra 3500HD as a heavy-duty truck for people who need serious towing and payload capability but do not want to give up comfort or upscale design. The GMC angle versus the closely related Chevrolet is a more premium look and feel: a quieter cabin, smarter storage, more polished trim progression, and stronger luxury differentiation at the top end with Denali.
The 2015 lineup ranges from a no-nonsense base work truck to the comfort-focused SLT and luxury-oriented Denali. Work-ready features include an integrated trailer brake controller, movable bed tie-downs, and a CornerStep rear bumper, while upper trims add an 8-inch touchscreen, heated leather seats, navigation, and premium audio.
What changed, by category
Powertrain
The gas powertrain joined the SLE and SLT trims. The existing heavy-duty gas V8 and Duramax diesel with Allison automatic transmission otherwise carried over.
Styling
GMC redesigned the exterior and interior, adding a new front end, projector-beam headlights, and a more distinctive Denali appearance.
Safety
Forward collision alert and lane departure warning joined the lineup. A rearview camera became standard on SLE and SLT.
Tech
Denali gained standard navigation and a standard touchscreen, while SLT gained a standard touchscreen. Bluetooth and USB ports became standard on SLE.
Structural
The redesigned truck gained a quieter cab with inlaid doors and triple door seals. A new Double Cab body style joined the range, and the cargo box added a CornerStep rear bumper and movable upper tie-downs.
2015 GMC Sierra 3500 specs and features by trim
| Feature | ||||
|---|---|---|---|---|
| Engine | V8, Flex Fuel, 6.0 Liter / V8, Turbo Diesel, 6.6 Liter / V8, 6.0 Liter / V8, Turbo Dsl, 6.6L | V8, Flex Fuel, 6.0 Liter / V8, Turbo Dsl, 6.6L / V8, 6.0 Liter | V8, Flex Fuel, 6.0 Liter / V8, Turbo Diesel, 6.6 Liter / V8, 6.0 Liter / V8, Turbo Dsl, 6.6L | V8, Flex Fuel, 6.0 Liter / V8, Turbo Dsl, 6.6L |
| Transmission | Automatic, 6-Spd HD w/Overdrive / Auto, 6-Spd Allison OD | Auto, 6-Spd Allison OD | Automatic, 6-Spd HD w/Overdrive / Auto, 6-Spd HD Overdrive | Auto, 6-Spd HD Overdrive |
| Drivetrain | 4WD | 4WD | 4WD | 4WD |
| Fuel Type | Flexible Fuel / Diesel / Gas | Flexible Fuel / Diesel / Gas | Flexible Fuel / Diesel / Gas | Flexible Fuel / Diesel |
| Horsepower | 360–397 hp | 360–397 hp | 360–397 hp | 360–397 hp |
| Torque | 380–765 lb-ft | 380–765 lb-ft | 380–765 lb-ft | 380–765 lb-ft |
| Max Towing | 13000–19600 lb | 13000–19600 lb | 13000–19600 lb | 13000 lb |
| Rear Legroom | 34.7–40.9 in | 34.7–40.9 in | 34.7–40.9 in | 40.9 in |
| Seats | 3–6 | 5 | 3–6 | 5 |
| Doors | 2–4 | 4 | 2–4 | 4 |
| Hill Descent Control | ||||
| Lane Departure Warning | ||||
| Park Assist | ||||
| Rear View Camera | ||||
| Alloy Wheels | ||||
| Fog Lights | ||||
| Heated Mirrors | ||||
| Power Moonroof | ||||
| Power Mirrors | ||||
| Privacy Glass | ||||
| Side Steps | ||||
| Front DVD Entertainment System | ||||
| Navigation System | ||||
| Rear DVD Entertainment System | ||||
| Satellite Radio | ||||
| Smartphone Interface | ||||
| Subwoofer | ||||
| Touch Screen Monitor | ||||
| USB Ports | ||||
| Auto-Dimming Interior Mirror | ||||
| Cooled Seats | ||||
| Dual Power Front Seats | ||||
| Dual-Zone Climate Control | ||||
| Heated Front Seats | ||||
| Heated Steering Wheel | ||||
| Integrated Garage Door Opener | ||||
| Leather Seats | ||||
| Leather-Wrapped Steering Wheel | ||||
| Memory Driver's Seat | ||||
| Power Adjustable Pedals | ||||
| Power Driver Seat | ||||
| Remote Start | ||||
| Remote Keyless Entry | ||||
| Tilt Wheel | ||||
| Tilt/Telescoping Steering Wheel | ||||
Frequently asked questions
Was the 2015 GMC Sierra 3500HD fully redesigned?
Yes. The 2015 Sierra 3500HD began a new generation with redesigned exterior and interior styling, a quieter cab, a new Double Cab body style, and updated cargo-box hardware.
What changed on the 2015 GMC Sierra 3500HD compared with 2014?
The truck around the engines changed substantially for 2015. GMC introduced a new body and cabin, improved cab sealing, projector-beam headlights, a CornerStep rear bumper, movable bed tie-downs, new driver-assist features, and more standard cabin technology on several trims.
Did the 2015 GMC Sierra 3500HD get new engines?
No major engine replacement defined the 2015 redesign. The heavy-duty gas V8 and the Duramax diesel with Allison automatic transmission carried over, although the gas powertrain joined the SLE and SLT trims.
What safety technology was new on the 2015 GMC Sierra 3500HD?
Forward collision alert and lane departure warning joined the lineup for 2015. A rearview camera also became standard on the SLE and SLT trims.
What stands out about the 2015 GMC Sierra 3500HD Denali?
The 2015 Denali is the luxury-focused version of the redesigned heavy-duty truck. It has distinctive Denali styling, heated and cooled leather front seats, a heated steering wheel, an 8-inch driver display, navigation, and Bose audio.
2015 GMC Sierra 3500 Reviews
What owners are saying about the 2015 GMC Sierra 3500.
4.2
2015 GMC Sierra 3500
(162 reviews)
“The headlights are definitely a failure! Extremely dim... Very stressful to drive at night.”
“This truck needs to have a tire pressure monitoring system available. Also, an optional rear seat fold-down, similar to that of the Yukon, should be available on the crew cabs.”