The Best GMC Repair in Longmont, CO

Compare the highest-rated gmc repair mechanics in Longmont, Colorado. All shops are licensed, insured, and verified through our rigorous screening process.

#1

A1 Auto & Diesel Specialists

4.8
(240 reviews)
Verified

A1 Auto is widely regarded as the premier independent shop in Longmont for GM trucks, particularly known for their expertise in complex diesel and transmission systems. They have built a strong reputation for honest diagnostics, high-quality workmanship, and the ability to handle everything from routine maintenance on a Sierra 1500 to major repairs on a heavy-duty Duramax.

2255 Miller Dr, Longmont, CO 80501

Specialties & Features

Duramax diesel service
Allison transmission repair
Heavy-duty truck suspension

Business Information

Years in Business:12 years
Licensed:Yes
Insured:Yes
#2

Tynan's GMC Service & Parts

4.4
(180 reviews)
Verified

While part of the Tynan's Auto Group dealership network, their dedicated service department functions as a specialist center for GMC vehicles. They are the top choice for owners wanting factory-trained technicians, genuine GM parts, and specialized diagnostic tools for the latest models, including Denali electronics and complex 10-speed transmissions.

2363 Ken Pratt Blvd, Longmont, CO 80501

Specialties & Features

Denali luxury features and electronics
EcoTec engine diagnostics
Towing package maintenance

Business Information

Years in Business:25 years
Licensed:Yes
Insured:Yes
#3

Pro Lube Auto & Diesel

4.6
(150 reviews)
Verified

A well-established, family-owned shop known for its personalized service and broad mechanical expertise. They are a strong alternative for GMC owners seeking reliable service on drivetrain components, 4WD systems, and general maintenance without the dealership price point. They receive consistent praise for their transparency and customer care.

700 Main St, Longmont, CO 80501

Specialties & Features

4WD and towing system service
Transmission repair
EcoTec engine diagnostics

Business Information

Years in Business:18 years
Licensed:Yes
Insured:Yes

Why These Are the Top GMC Repair Auto Repair Shops in Longmont

** The GMC repair market in Longmont, Colorado, is robust and competitive, reflecting the region's high ownership rates of trucks and SUVs for both personal and commercial use. The quality of service providers is generally high, split between the factory-backed expertise of the Tynan's GMC dealership and several highly competent independent shops. **Competition Level:** High. There is a healthy competition between the dealership and independent specialists. Independents like A1 Auto and Pro Lube compete on price, personalized service, and deep mechanical expertise, particularly on older or heavily modified trucks. The dealership competes with OEM training, specialized tools for the latest computer systems, and factory warranty adherence. **Average Quality:** The top-tier shops provide excellent, expert-level service. Customers have clear choices depending on their needs: dealership for cutting-edge technology and warranty work, or independents for cost-effective, experienced mechanical repairs. **Typical Pricing:** Pricing is tiered. The dealership (Tynan's) typically commands a premium, with higher labor rates and parts costs. Independent specialists offer more competitive labor rates, often 15-30% lower, while maintaining high-quality, aftermarket, or rebuilt parts. A complex job like an Allison transmission rebuild or Duramax injector replacement will be a significant investment at any top shop but can be more economically approached at an independent specialist.

High Ratings

4.7+ star average from verified customer reviews

Fully Licensed

All shops are properly licensed and insured

Proven Experience

10+ years average experience in the industry

Local Experts

Familiar with Longmont regulations and climate