Onyx Black 2026 GMC Sierra 1500 AT4X 4WD 10-Speed Automatic 3.0L I6 10-Speed Automatic, 4WD, Obsidian Rush Leather.GMC Dealership Serving Boulder, CO Drivers – Mike Maroone GMC GMC Sales, Service, and Parts in Boulder, CO If you have been longing to get into a new GMC close to Boulder, CO, then right now is an ideal opportunity to find your next auto at a low cost, here at Mike Maroone GMC. Enjoy Free Delivery anywhere in Colorado. Our GMC Truck line is headed by the Sierra 1500, 2500 and 3500, each new GMC model can be found here at our Boulder, CO dealership. Discover your new GMC in Boulder now for a test spin of your dream car. Price includes: $1500 – Buick & GMC Consumer Cash Program. Exp. 01/02/2026 $250 – December Buick GMC Holiday Event Bonus Cash. Exp. 01/02/2026 $500 – GM Bonus Cash. Exp. 01/02/2026