Policy Background: Transition to China VI Emission Standards and Timeline for Phasing Out Older Vehicles. With the government's intensified efforts to combat air pollution, the China VI emission standards have been fully implemented. According to requirements issued by the Ministry of Ecology and Environment and other relevant ministries, all heavy-duty diesel vehicles—including most special-purpose vehicles—must comply with the China VIb emission standard starting from July 2021. In coastal cities such as Taizhou, the phase-out and replacement of older vehicles (China III and below) has accelerated. Public information indicates that numerous regions across China have introduced subsidy policies for scrapping older diesel trucks, e.g., Taizhou City offers subsidies ranging from RMB 10,000 to 40,000 for early retirement of operational China III (or lower) diesel trucks during 2023–2025. For municipal sanitation departments, this means that when procuring new vehicles, compliance with China VI standards must be ensured—not only for the new units themselves but also in coordination with subsidy applications for scrapping older vehicles, thereby maximizing financial efficiency. Meanwhile, demand for operations such as urban drainage pipe desilting and river remediation continues to rise. The Dongfeng double-cab sludge suction truck (blue license plate, 3-cubic-meter capacity), with its compact dimensions, excellent maneuverability, and operational flexibility, has become a preferred choice among municipal authorities in southern China’s water-rich regions—including Taizhou. Case Study: Sludge Suction Truck Procurement by a Municipal Sanitation Department in Taizhou. In 2025, a municipal sanitation department in Taizhou planned to procure one blue license plate, 3-cubic-meter Dongfeng double-cab sludge suction truck to address aging drainage network renovation tasks within its jurisdiction. The department previously operated two China III sludge suction trucks, both having reached their mandatory scrappage age and suffering from deteriorating conditions and high maintenance costs. Procurement requirements were clearly defined: the vehicle must meet China VI emission standards; feature high-pressure cleaning and vacuum suction capabilities; possess dimensions suitable for navigating narrow alleys in historic urban districts; and withstand Taizhou’s hot, humid, and rainy climate. Following an open tender process, Chengli Special Purpose Vehicle Co., Ltd. delivered a sludge suction truck built on a Dongfeng chassis (model reference: CLW5070GSSD6 or similar models listed on official announcement platforms). Key configurations included: a 3-cubic-meter tank volume, high-pressure cleaning pump, vacuum suction system, and corrosion-resistant coatings and sealing components specially optimized for coastal environments. According to publicly available tender information, the project budget was capped at approximately RMB 319,000, while the final winning bid price stood at around RMB 260,000 (based on local procurement practices)—significantly lower than quotations from imported brands or custom-upfitters. Chengli’s China VI Solution: Targeted Optimization for Humid Environments. In coastal areas like Taizhou—characterized by high humidity, high salinity, and frequent rainfall—the primary challenges facing sludge suction trucks are corrosion and seal failure. Chengli Special Purpose Vehicle emphasized three key advantages in this delivery solution: 1. Anti-corrosion Coating for Tank and Chassis: The tank interior features an epoxy resin + polyurethane composite coating; the exterior is coated with high-adhesion anti-rust primer; and critical components—including the chassis—are galvanized. Customer feedback indicates no visible rust on the chassis after one year of operation, representing a ~60% reduction in coating peeling compared to previous-generation vehicles. 2. Seal Durability in Humid-Hot Conditions: All hydraulic cylinders, vacuum p