I. Case Background: Sewage Treatment Vehicle Procurement Requirement of a Municipal Sanitation Department in Dalian In winter 2025, a municipal sanitation department in Dalian planned to procure a batch of Dongfeng Yizhan-style sewage treatment vehicles to address mixed industrial and domestic wastewater treatment needs within its jurisdiction. The region experiences minimum winter temperatures as low as -20°C, imposing stringent requirements on vehicle cold-start performance and low-temperature hydraulic system stability. The procuring party mandated compliance with China VI emission standards, full official vehicle type approval (for registration), and suitability for frequent start-stop operational scenarios. After multiple rounds of tendering, Chengli Special Automobile (models such as CLW5070GSSD6, etc.) secured the contract with its low-temperature adaptation solution and cost-effectiveness advantage, delivering five units at an approximate unit price of RMB 350,000 (based on publicly available tender information). II. Comparative Parameter Table of Five Mainstream Models Parameter Item Chengli CLW5070GSSD6 Chengli CLW5180GSSD6 Competitor Model A Competitor Model B Chengli Customized Model Chassis Brand Dongfeng Dongfeng Sinotruk FAW Jiefang Dongfeng Emission Standard China VI China VI China VI China VI China VI Tank Capacity (m³) 5 8 6 7 5 Engine Power (kW) 85 100 90 95 85 Cold-Start System Cold-start assist + preheating Cold-start assist + dual preheating Standard preheating Cold-start assist Cold-start assist + electric heating Hydraulic System Operating Temperature Range -25°C to 60°C -25°C to 60°C -15°C to 50°C -20°C to 55°C -30°C to 65°C Superstructure Material Stainless steel + anti-corrosion coating Stainless steel + anti-corrosion coating Carbon steel Stainless steel Stainless steel + dual-layer coating Official Type Approval Model Number CLW5070GSSD6 CLW5180GSSD6 ZZT5070GSS CA5070GSS CLW5070GSSD6-Customized Reference On-Road Price (RMB 10,000) Approx. 30–35 Approx. 38–45 Approx. 32–38 Approx. 35–40 Approx. 32–36 Delivery Lead Time (days) 10–15 12–18 14–20 15–22 10–15 Note: Above parameters are based on Chengli Special Automobile’s official type approvals (CLW5070GSSD6, CLW5180GSSD6) and publicly released tender documents; price ranges reflect local procurement conventions. III. Dimensional Comparative Analysis: Focus on Dalian’s Low-Temperature Environment 1. Freeze-Resistant Starting Performance Dalian’s winter temperatures frequently drop below -15°C. Competitor Model A, equipped only with a standard preheating system, exhibits approximately a 30% reduction in successful cold starts at -20°C. In contrast, the Chengli CLW5070GSSD6 employs cold-start assist plus preheating technology, enabling reliable one-time starting even at -25°C. The Chengli customized model further upgrades to an electric heating system, reducing startup time to within 15 seconds. Feedback from the procuring party confirms no cold-start failures occurred during actual operations. 2. Low-Temperature Hydraulic Stability The hydraulic system is critical to sewage treatment vehicle functionality; increased hydraulic oil viscosity at low temperatures causes sluggish actuation. Competitor Model B’s hydraulic system operates within a temperature range of -20°C to 55°C, exhibiting significant efficiency degradation below -15°C. Chengli models utilize low-