I. Case Background: Procurement Requirement of a Municipal Sanitation Department in Taiyuan City In winter 2025, a municipal sanitation department in a district of Taiyuan City planned to procure a batch of blue license plate sewage treatment vehicles to address pipeline blockages and sewage treatment needs in aging residential communities. According to publicly released tender information, the project budget was capped at approximately RMB 344,000, with the following core vehicle requirements: • Blue license plate, drivable with C-class driver’s license; • Overall vehicle length ≤ 6 meters; • Gross vehicle weight ≤ 4.5 tons; • Equipped with Dongfeng D6 chassis, meeting China VI emission standards, and featuring cold-weather starting capability (operable in Taiyuan’s winter temperatures ranging from −15°C to −25°C). • Tank capacity ≥ 3 m³, equipped with high-pressure cleaning and sewage recirculation systems. • Hydraulic system must operate stably at low temperatures; winter maintenance plan must be clearly defined. After multiple rounds of technical evaluation, Chengli Special Purpose Vehicle Co., Ltd. (located at No. 1 Chengli Avenue, Economic Development Zone, Suizhou City, Hubei Province) won the bid with its Dongfeng D6 blue license plate sewage treatment vehicle solution. This solution is based on the official announcement parameters of model CLW5070GSSD6 and features customized configurations tailored to Taiyuan’s local climatic conditions. II. Core Engine Comparison: Differences Among 85 kW / 100 kW / 120 kW Engines and Fuel Consumption Analysis In the selection of blue license plate sewage treatment vehicles, engine power directly determines operational efficiency and fuel cost. Below is a comparative analysis under typical operating conditions in Taiyuan: Engine Model | Power (kW) | Max Torque (N·m) | Fuel Consumption (L/100 km) | Application Scenario | Cold-Start Performance ---|---|---|---|---|--- 85 kW (~115 HP) | 85 | 280 | 10–12 | Urban flat roads, light-load operations | Requires optional preheating device; stable above −15°C 100 kW (~136 HP) | 100 | 330 | 12–14 | Urban mixed-road conditions, standard operations | Standard preheating; stable above −20°C 120 kW (~163 HP) | 120 | 380 | 14–16 | Mountainous terrain, heavy-load, frequent start-stop cycles | Standard preheating + auxiliary heating; stable above −25°C Case Selection: The municipal sanitation department ultimately selected the 100 kW engine (referencing CLW5070GSSD6 announcement specifications), primarily for the following reasons: • Balanced Fuel Efficiency: Under urban mixed-road conditions, the 100 kW engine achieves ~12–14 L/100 km fuel consumption—approximately 2 L/100 km less than the 120 kW engine. Assuming an annual mileage of 20,000 km, this translates to ~RMB 3,000 in annual fuel savings. • Sufficient Power Output: Within the gross vehicle weight limit for blue license plate vehicles, the 100 kW engine fully meets standard sewage recirculation operational requirements—no need to over-specify higher power. • Low-Temperature Adaptability: Standard preheating device ensures reliable cold starts under Taiyuan’s typical winter temperatures (≤ −20°C). III. High-Altitude & Plain Adaptation: Special Optimization for Taiyuan’s Winter Operating Conditions Taiyuan lies in the eastern part of the Loess Plateau, at an elevation of ~800 meters. Winters are dry and frigid, with minimum temperatures reaching −25°C. To address these challenges, Chengli Special Purpose Vehicle enhanced the following configurations in its solution: 1. Cold-Weather Starting Capability • Fuel System: Uses −35# diesel fuel, optionally paired with a fuel heater to prevent waxing at low temperatures. • Battery: Upgraded