I. Introduction: Key Selection Challenges for Sewage Treatment Vehicles in Harbin’s Extreme Cold Environment Harbin, located in Northeast China’s frigid region, experiences winter temperatures frequently dropping below -30°C. Municipal sanitation departments face severe operational challenges with sewage treatment vehicles—cold-start reliability, low-temperature hydraulic system stability, and winter maintenance strategies are the top concerns for procurement entities. In 2025, a municipal sanitation department launched a tender to procure a batch of CN6-emission-compliant sewage treatment vehicles for urban sewer network cleaning and emergency response. After multiple rounds of evaluation, Chengli Special Purpose Vehicle Co., Ltd.’s blue-plate Dongfeng 3308 mm wheelbase sewage treatment vehicle (model CLW5070GSSD6) stood out among competitors. To date, approximately three units have been delivered, and customer feedback confirms stable performance under low-temperature conditions. This article analyzes the winning proposal and real-world operational experience of this model from the perspective of comparing blue-plate (C-license) versus yellow-plate (B-license) vehicles, supported by an authentic government procurement case—providing practical reference for sanitation authorities operating in similar harsh environments. II. Blue-Plate (C-License) vs. Yellow-Plate (B-License): Differences in Operating Costs and Application Scenarios In government procurement, the driver’s license category required for sewage treatment vehicles directly impacts staffing configuration and operating costs. The table below compares key differences between blue-plate C-license vehicles (gross vehicle weight ≤ 4.5 tons) and yellow-plate B-license vehicles (gross vehicle weight > 4.5 tons): Comparison Item | Blue-Plate C-License Vehicle (e.g., CLW5070GSSD6) | Yellow-Plate B-License Vehicle (e.g., Dongfeng Dolika 8-cubic-meter model) Driver’s License Requirement | C1/C2 license sufficient; lower driver qualification threshold | Requires B2 or higher license; higher driver recruitment cost Gross Vehicle Weight | Approximately ≤ 4.5 tons (as per official announcement limit) | 8–12+ tons Tank Capacity | Approximately 3–5 cubic meters (based on CLW5070GSSD6 specifications) | Approximately 6–8 cubic meters Purchase Cost | Approx. RMB 98,000–115,000 (Chengli’s 2026 tax-inclusive pricing reference) | Approx. RMB 145,000–178,000 (Chengli’s 8-cubic-meter water tanker pricing reference) Annual Operating Cost (including insurance, road tolls, fuel) | Approx. RMB 20,000–30,000/year (estimated, subject to usage frequency) | Approx. RMB 40,000–50,000/year (higher due to vessel & vehicle tax and insurance premiums) Applicable Scenarios | Narrow urban alleys, residential communities, township roads, temporary emergency response | Main arterial roads, large-scale sewage ponds, long-distance transport Low-Temperature Performance | Requires anti-freeze equipment (Chengli provides standard cold-weather starting system) | Also requires anti-freeze measures, but operates at higher hydraulic system pressure Case Analysis: In its 2024 procurement, a district urban management bureau initially favored yellow-plate models for greater capacity. However, considering the local driver shortage—B-license drivers command monthly salaries ~RMB 2,000 higher than C-license drivers—the bureau ultimately selected Chengli’s blue-plate CLW5070GSSD6 solution. Per local procurement practice, the blue-plate model’s unit price is approximately RMB 105,000, saving about RMB 40,000 per unit compared to yellow-plate alternatives, while also reducing driver training duration to within one week. III. Harbin Case Study: Detailed Winning Proposal for Chengli’s Blue-Plate Sewage Treatment Vehicle 1. Vehicle Specifications and Configuration Chengli’s CLW5070GSSD6 sewage treatment vehicle is built upon the Dongfeng 3308 mm wheelbase chassis and complies with CN6 emission standards. Key parameters (per MI