I. Background: First Procurement by a Municipal Sanitation Department in Shaoxing. Located in the Jiangnan water town region, Shaoxing features a dense network of rivers and a prolonged rainy season; its municipal sanitation department handles large volumes of domestic and industrial wastewater annually. In 2023, a district Urban Management Bureau in Shaoxing (hereinafter referred to as the 'Customer') planned to procure a batch of blue-license-plate sewage treatment vehicles for sewage suction, transportation, and preliminary treatment along urban main roads and surrounding rural areas. According to publicly released tender information, the Customer’s budget was approximately RMB 170,000–226,000 per unit, requiring vehicles eligible for blue license plates (drivable with Class C driver’s license) and suitable for high-humidity, rainy environments. After comprehensive evaluation, the Customer ultimately selected Chengli Special Purpose Vehicle Co., Ltd.’s Dongfeng D6 Chassis Sewage Treatment Vehicle (Model CLW5070GSSD6). This model is modified based on the Dongfeng D6 chassis, fully compliant with official announcements and meeting China VI emission standards—thus legally eligible for blue license plate registration. The initial procurement volume was five units, priced at approximately RMB 160,000 per unit (based on local procurement practice), with a total budget of about RMB 904,000. Chengli Sales Manager Zhang Yue (Phone: ) provided end-to-end service—from model selection and parameter confirmation to delivery. The Customer commented: 'After the first batch was delivered, we primarily used these vehicles for domestic sewage suction and transport, operating at high frequency—approximately 8–10 hours daily.' II. Shortcomings and Challenges of the Initial Procurement. Following three months of intensive summer operation (with even higher operational frequency during the rainy season), the Customer identified the following issues with the initial batch: Insufficient Rust Protection: Due to Shaoxing’s high ambient humidity—and frequent exposure of the vehicle’s tank and piping to wastewater and rain—visible corrosion appeared on tank and pipe surfaces; rusting at some bolted joints affected both aesthetics and structural integrity. Inadequate Sealing Component Durability: Under hot-humid conditions, sealing rings and rubber hoses aged prematurely, causing minor leakage and compromising operational efficiency and safety. Unstable High-Load Performance: During continuous operation, the vacuum pump and hydraulic system overheated, indicating insufficient capability to sustain high-frequency usage. During an internal meeting, the Customer stated: 'Although the price was competitive, the subsequent maintenance costs and efficiency losses were unforeseen. We require a more durable version—especially optimized for southern China’s humid climate.' Key Pain Points Summarized: Weak anti-corrosion coating, short sealing component service life, and poor stability under high-load operation. III. Upgraded Requirements: Re-selecting Chengli and Customizing an Improved Version. In early 2024, the Customer planned to purchase three additional sewage treatment vehicles, with a revised budget of approximately RMB 203,000–249,000 per unit. This time, the Customer contacted Chengli directly and specified clear upgrade requirements: Enhanced Anti-Corrosion Coating: Tanks, piping, and all metal components must feature hot-dip galvanization or epoxy resin coating, ensuring no visible rust within three years. Weather-Resistant Sealing Components: Seals must be made from silicone rubber or fluororubber to withstand high humidity and acidic/alkaline environments. High-Load Optimization: Upgrade the vacuum pump cooling system and hydraulic oil radiator to ensure stable continuous operation for over eight hours. Based on the Customer’s feedback, Chengli’s engineering team implemented targeted improvements to the CLW5070GSSD6 model: Added interna