I. Project Background: Sewage Treatment Truck Procurement Requirement of a Municipal Sanitation Department in Wenzhou City In summer 2025, a municipal sanitation department in a district of Wenzhou City planned to procure a batch of new Dongfeng sewage treatment trucks to meet the growing demand for urban sewage treatment capacity. Located along the southeast coast, this region experiences hot, humid weather and frequent rainfall during the rainy season—posing stringent requirements on vehicle chassis corrosion resistance, sealing component durability, and stability under high-load operation. The procurement budget was capped at approximately RMB 2.238 million, with mandatory compliance to China VI emission standards, rapid delivery capability, and long-term after-sales support. According to publicly released tender information, the department selected Chengli Special Purpose Vehicle Co., Ltd. as the supplier, delivering five Dongfeng-chassis sewage treatment trucks. Chengli secured the bid by leveraging its factory-direct sales advantage, comprehensive official vehicle announcements (e.g., CLW5070GSSD6), and lifetime after-sales service commitment. This article provides an in-depth technical and procurement analysis of the case, covering engine selection, fuel consumption comparison, and regional adaptability. II. Engine Comparison: Power Differences Among 85 kW / 100 kW / 120 kW Options As a specialized vehicle, the core powertrain of a sewage treatment truck directly impacts operational efficiency and total cost of ownership. For this Wenzhou project, Chengli offered three engine options based on the Dongfeng chassis—all compliant with MIIT-issued official vehicle parameters (e.g., CLW5070GSSD6). Detailed comparison is as follows: Parameter 85 kW Engine (116 HP) 100 kW Engine (136 HP) 120 kW Engine (163 HP) Applicable Scenario Light-duty urban operations & short-haul transport Medium-duty, routine municipal operations Heavy-duty operations, complex terrain or frequent uphill driving Maximum Torque Approx. 300 N·m Approx. 400 N·m Approx. 500 N·m Fuel Consumption (per 100 km) Approx. 18–22 L Approx. 20–25 L Approx. 24–30 L Suitable Regions Plains (altitude ≤2,000 m) or mountainous areas Plains (altitude ≤2,000 m) or mountainous areas Plains (altitude ≤2,000 m) or mountainous areas Price Impact (Reference) Chassis cost approx. RMB 10,000–20,000 lower Mid-range pricing Chassis cost approx. RMB 20,000–30,000 higher Performance in Hot-Humid Environments Requires enhanced anti-corrosion coating Sealing components must be high-temperature resistant Cooling system requires optimization under high-load conditions Note: Data above is compiled from Chengli’s product database and Dongfeng chassis official announcement parameters. Fuel consumption figures represent theoretical values; actual consumption varies depending on road conditions and load. III. Fuel Consumption Comparison and Cost Analysis For the Wenzhou project, the client selected the 100 kW engine as the primary configuration, based on the following considerations: Fuel Economy: Under routine municipal operations (e.g., sewage suction and transportation), the 100 kW engine achieves approx. 22–25 L/100 km fuel consumption—saving 15%–20% compared to the 120 kW engine. Over time, this significantly reduces operating costs. Based on local procurement practice, each vehicle runs approx. 20,000 km annually; at current diesel prices, annual fuel savings amount to approx. RMB 5,600–8,950 per unit. High-Load Performance: Given Wenzhou’s frequent rainy season, sewage treatment trucks often operate continuously for 8–12 hours. The 100 kW engine offers sufficient torque reserve to reliably drive sewage pumps and vacuum systems, avoiding overheating-induced shutdowns. Maintenance Convenience: Dongfeng chassis are covered by nationwide warranty services, while Chengli provides lifetime after-sales support for the superstructure. The 100 kW engine