The 2021 GMC Sierra 1500 SLT in Onyx Black with Jet Black interior delivers premium full-size truck comfort, smooth diesel-style torque, and practical 4WD capability for drivers who want more than just a plain work truck. Powered by a 3.0L I6 engine and paired with a 10-speed automatic transmission, this Sierra SLT offers confident towing and hauling ability, composed highway manners, and the kind of upscale everyday drivability that makes it feel equally at home on the ranch, the road, or the jobsite. With 90,275 miles, this Crew Cab still brings strong value, broad buyer appeal, and premium truck utility in a package that knows how to work without feeling stripped down.

Entertainment and Connectivity Features
• Large touchscreen infotainment display
• Apple CarPlay integration
• Android Auto integration
• Bluetooth® hands-free connectivity
• USB charging and media ports
• Steering wheel mounted audio and phone controls
• Voice recognition capability
• Wi-Fi hotspot capability
• Navigation capability
• Digital driver information display

Added Features
• SLT trim package
• Onyx Black exterior
• Jet Black interior
• Four-wheel drive capability
• 3.0L I6 performance
• Crew Cab configuration
• Premium interior appointments
• Strong towing and hauling appeal
• Broad personal-use and work-truck versatility
• Clean upscale GMC styling

Safety Features
• Automatic Emergency Braking
• Forward Collision Alert
• Lane Keep Assist with Lane Departure Warning
• Following Distance Indicator
• HD rear vision camera
• Electronic Stability Control
• Anti-lock braking system
• Tire pressure monitoring system
• Advanced airbag system
• Teen Driver capability

Standard Features
• LED headlamps and LED daytime running lights
• Premium alloy wheels
• Dual-zone automatic climate control
• Power windows and door locks
• Push-button start capability
• Spacious Crew Cab interior
• Fold-up rear seating for added interior flexibility
• Tilt and telescoping steering wheel
• Rear seat air vents
• SLT-specific upscale styling accents

Mechanical Features
• 3.0L I6 engine
• 10-speed automatic transmission
• Four-wheel drive
• Heavy-duty suspension capability
• Four-wheel disc brakes
• Electric power steering
• Strong towing and hauling performance
• Smooth power delivery for daily driving and heavy use
• Built for work, travel, and everyday truck use
• Proven full-size truck practicality

Why drivers choose Port Lavaca Auto Group for their next vehicle

• Trusted dealership serving Texas drivers with transparent, pressure-free buying experiences
• Large selection of quality SUVs, trucks, and cars ready for immediate delivery
• Knowledgeable product specialists who help match drivers with the right vehicle
• Flexible financing options for a wide range of buyers
• Ongoing customer support and service after the sale
• Strong reputation backed by consistent five-star Google reviews

Customer Review Highlight

We shopped around quite a bit before buying, and Port Lavaca Auto Group stood out right away. They were professional, easy to talk to, and made sure everything was clear from start to finish.
Heather W., March 2026

From its practical 4WD capability and premium SLT trim to its roomy Crew Cab comfort and strong everyday truck utility, the 2021 GMC Sierra 1500 is built for drivers who want full-size truck strength, upscale comfort, and value in a pickup that still knows how to earn its keep.