I. Project Background and Procurement Requirements In early 2026, the Urban Management Bureau of a district in Taizhou City, Zhejiang Province, launched a public tender for sewage treatment trucks, with a total procurement budget capped at approximately RMB 1.352 million, aiming to acquire two new Dongfeng-series sewage treatment trucks. Located along China’s southeast coast, the region experiences abundant annual rainfall and frequent operations during the rainy season; its hot, humid climate imposes exceptionally high demands on the corrosion resistance of both chassis and superstructure. The procuring entity explicitly stipulated in the tender documents that: the vehicles must deliver high-efficiency sewage treatment performance; the chassis must comply with China VI emission standards; the superstructure must feature anti-rust coating; and critical sealing components must be humidity-resistant to ensure reliable operation for over five years without frequent replacement. Chengli Special Purpose Vehicle Co., Ltd. (hereinafter referred to as “Chengli”) leveraged Dongfeng chassis platforms and integrated its extensive expertise in sanitation vehicle development to propose a customized solution based on the CLW5180GSSD6 model. Chengli ultimately secured the contract and delivered two units at a unit price of approximately RMB 480,000 (based on publicly available tender information). This article provides an in-depth analysis of the procurement rationale and technical advantages of this case, covering total cost of ownership (TCO) by service life, major overhaul intervals, depreciation characteristics, and more. II. Total Cost of Ownership (TCO) Analysis by Service Life Government procurement decisions must consider not only the initial acquisition cost but also the full lifecycle cost. Drawing upon actual operational data from Chengli’s sewage treatment trucks deployed in Taizhou, we conducted comparative TCO analyses across three service-life horizons—5 years, 8 years, and 10 years—(data synthesized from publicly disclosed tender information, Chengli after-sales records, and industry benchmarks). Cost Item 5-Year Cycle (RMB 10,000) 8-Year Cycle (RMB 10,000) 10-Year Cycle (RMB 10,000) Acquisition Cost (incl. tax & delivery) 48 48 48 Fuel/Electricity (estimated at 200 operating days/year) ~12 ~20 ~25 Maintenance & Repairs (incl. major overhauls) ~5 ~12 ~20 Insurance & Annual Inspection ~3 ~5 ~7 Residual Value (used-vehicle resale) ~−10 ~−6 ~−3 Total Cost of Ownership (TCO) ~58 ~79 ~97 Note: Figures above are derived from publicly available tender data and Chengli after-sales statistics; actual values may vary depending on real-world operating conditions. Major overhaul costs are estimated once at Year 5 and again at Year 8. As shown in the table, within the 5-year horizon—when the vehicle operates under optimal conditions—maintenance costs remain low, yielding a TCO of approximately RMB 580,000, representing the highest cost-effectiveness. At the 8-year mark, aging seals and component wear drive up major overhaul expenses, yet overall costs remain manageable. By the 10-year horizon, residual value declines sharply and maintenance costs rise significantly as a share of TCO; therefore, customers are advised to evaluate vehicle replacement planning between Years 8 and 10. III. Major Overhaul Intervals and Adaptation to Humid-Tropical Environments Taizhou’s coastal location subjects sewage treatment trucks to pronounced challenges from heat and humidity. To address these, Chengli enhanced the following key aspects in its solution: • Anti-Corrosion Coating: High-temperature powder coating and electrophoretic coating processes applied to critical structural components of both chassis and superstructure; validated via salt-spray testing to withstand over five years of coastal corrosion exposure. • Seal Durability: Critical sealing components—including sewage tank interfaces and pump seals—are fabricated from fluororubber, offering su