I. Case Background: First Procurement for a Newly Established Unit In autumn 2025, a newly established district-level municipal sanitation department in Urumqi urgently needed to procure sewage treatment vehicles due to newly built industrial parks and residential areas within its jurisdiction. As the unit had no prior experience purchasing special-purpose vehicles, it faced significant challenges in vehicle selection from scratch. Urumqi’s winter temperatures frequently drop below -25°C, imposing stringent requirements on vehicle cold-start performance, hydraulic system stability, and routine maintenance. Selecting a blue-plate sewage treatment vehicle capable of meeting daily operational needs while ensuring reliable operation in extreme cold became the department’s core challenge. According to local procurement practices, the budget was capped at approximately RMB 344,000, requiring the vehicle to be blue-plate (drivable with a Class C1 driver’s license), equipped with sewage suction, transportation, and preliminary separation capabilities, and delivered by the end of December 2025. Upon receiving the inquiry, Chengli Special Purpose Vehicle Co., Ltd. (“Chengli”) promptly engaged and provided comprehensive technical consultation and solution support. II. Vehicle Selection Process: Precise Matching from Technical Specifications to Winter Adaptability Based on the department’s requirements, Chengli’s technical team recommended the CLW5070GSSD6 sewage treatment vehicle built on the Dongfeng D6 chassis. With a tank capacity of approximately 5 m³, this model complies with blue-plate regulations and holds complete official announcements, enabling nationwide registration. In Urumqi’s harsh winter conditions, key considerations included freeze resistance and low-temperature hydraulic system stability. 1. Cold-Start Freeze Resistance: The CLW5070GSSD6 is equipped as standard with a low-temperature preheating system, including an engine cold-start preheating device and insulated fuel tank lining—ensuring reliable startup even at -30°C. Per the MIIT announcement parameters (CLW5070GSSD6), this model features a China VI-compliant Dongfeng D6 chassis with engine power output ranging from 80–95 kW, suitable for use in severely cold regions. 2. Low-Temperature Hydraulic Stability: The hydraulic system is critical for sewage suction and tank lifting operations. For the Urumqi project, Chengli customized low-temperature hydraulic oil (pour point: -35°C) and reinforced hydraulic line insulation sleeves to prevent oil solidification and system failure in freezing conditions. Additionally, hydraulic piping adopts a double-seal design to minimize leakage risks caused by thermal contraction at low temperatures. 3. Winter Maintenance Plan: Chengli provides an accompanying “Winter Operation Manual,” covering daily startup procedures, antifreeze replacement intervals (recommended every two years), and winter-specific hydraulic oil change standards. After-sales service commitments include nationwide chassis warranty coverage, lifetime upfit support, and 24-hour express delivery of emergency winter spare parts—effectively addressing users’ operational concerns. Ultimately, the department selected Chengli as the winning bidder through a public tender process in November 2025. According to publicly available tender information, the winning bid price was approximately RMB 275,000, inclusive of the vehicle, spare tire, onboard tools, and first maintenance service. III. Delivery and Trial Operation: Real-World Validation under Subzero Conditions After contract signing, Chengli completed production in early December 2025 and delivered the vehicle to Urumqi via dedicated transport. On-site, Chengli technicians conducted a three-day on-site training program covering vehicle operation, winter startup procedures (requiring 5–10 minutes of preheating), hydraulic system inspection, and basic troubleshooting. The department