I. Background: Sludge Transportation Challenges Faced by a Municipal Sanitation Department in Jiaxing, Zhejiang Province Jiaxing, as a key ecological city in the Yangtze River Delta region, imposes stringent requirements on environmental protection and operational efficiency for municipal sanitation vehicles. In 2022, a district-level municipal sanitation department in Jiaxing encountered the following pain points during routine sludge collection and transportation operations: Aging Fleet: Existing outdated dump trucks failed to meet emission standards, suffered from high failure rates, and did not comply with China VI environmental regulations. Road Access Restrictions: Narrow urban roads hindered passage of large vehicles; blue-plate models (drivable with Class C driver’s license) were urgently needed to enhance operational flexibility. Load Capacity Matching: Average single-trip sludge volume was approximately 2–3 tons; a 3 m³ vehicle perfectly matched daily operational frequency, avoiding wasted transport capacity. After comprehensive evaluation, the department selected a blue-plate, 3 m³ sludge dump truck built on the Dongfeng D6 chassis, supplied by Chengli Special Purpose Vehicle Co., Ltd. (hereinafter referred to as “Chengli”). This decision was based on Chengli’s strong professional reputation in the sanitation sector—its products feature complete official announcements (e.g., model CLW5030ZLJD6), and it has served over 500 municipal sanitation units nationwide, including local property management companies and sanitation stations in Zhejiang Province. II. Initial Contract in 2022: Procurement Details of Dongfeng D6 Blue-Plate, 3 m³ Sludge Dump Truck In June 2022, the department procured six units of the Dongfeng D6 blue-plate, 3 m³ sludge dump truck via public tender. According to publicly available tender information, the total procurement budget was capped at approximately RMB 599,000–732,000, with unit price ranging from RMB 90,000 to 110,000. Chengli won the bid due to the following advantages: Direct Factory Sales: Compared with 4S dealership channels, same-specification vehicles offered cost savings of approximately RMB 8,000–15,000 per unit, directly reducing procurement expenses. China VI Compliance: All models fully comply with China VI emission standards, ensuring normal operation and annual inspection within Jiaxing’s urban area. Rapid Delivery: Standard models are delivered within 7–15 days; all six initial units arrived within 12 days after contract signing, with no inventory backlog issues. Complete Announcement Documentation: The Dongfeng D6 chassis paired with the sludge-dump body is fully documented under official announcements (e.g., CLW5030ZLJD6), enabling nationwide registration without additional modifications. Key Specifications (based on MIIT announcement parameters and local procurement practices): Item Parameter Chassis Model Dongfeng D6 (Dongfeng Automobile Co., Ltd.) Engine China VI diesel engine, rated power approx. 85 kW Cab Single-row, tiltable cab with air conditioning and power steering Body Capacity 3 m³ (actual sludge loading capacity: approx. 2.5–3 tons) Dumping Mechanism Hydraulic lifting, rear tipping Emission Standard China VI License Plate Type Blue plate (Class C driver’s license required) Superstructure Brand Chengli Special Purpose Vehicle Co., Ltd. III. Operational Performance: Two-Year Field Feedback From July 2022 to June 2024, the initial batch of six Dongfeng D6 blue-plate, 3 m³ sludge dump trucks operated daily for the municipal sanitation department in the aforementioned district of Jiaxing. Customer feedback included: Operational Efficiency: An average of 5–6 sludge collection points serviced per day; round-trip distance approx. 40 km; fuel consumption economical (approx. 12–14 L/100 km). Maneuverability: Blue-plate configuration enables access to narrow areas such as old residential communities and farmers’ markets, eliminating the need for additional traffic cont