I. Scenario Introduction: Starting with a 'Returning Customer' In Zunyi, Guizhou Province, Mr. Li, a vehicle administrator at a municipal sanitation department, recently called Chengli Special Purpose Vehicle's sales manager, Ms. Zhang Yue (), again. This is not his first order: one year ago, his unit purchased two Chengli-manufactured Dongfeng D6 blue-plate 3 m³ sludge dump trucks for urban pipeline desilting and sludge transportation. This time, he plans to add one more unit of the same model for a newly launched street environmental maintenance project. 'Customer referrals are extremely common in the sanitation equipment procurement industry,' Mr. Li said over the phone. 'The previous two units operated throughout an entire rainy season in Zunyi’s humid, subtropical climate—without rust on the chassis or hydraulic system leaks. They’ve proven far more reliable than other brands we previously used. This time, we won’t go through a complex tendering process; instead, we’ll place the order directly via the 'repeat customer purchase' channel.' This case exemplifies Chengli Special Purpose Vehicle’s 'word-of-mouth order generation' model in government procurement—where trust built upon real-world operational experience enables efficient, low-cost purchasing decisions. II. Case Background: Procurement Requirements of a Municipal Sanitation Department in Zunyi Zunyi is located in northern Guizhou Province, featuring a humid, subtropical climate with a concentrated rainy season from May to September and annual precipitation exceeding 1,000 mm. Such climatic conditions impose stringent requirements on sludge dump trucks’ corrosion resistance and sealing performance. The department is responsible for routine desilting and maintenance of approximately 30 km of urban drainage pipelines, requiring a blue-plate (drivable with a Class C1 driver’s license) 3 m³ sludge dump truck primarily for: - Transporting high-moisture sludge (approx. 80% water content) following routine pipeline desilting; - Clearing mud and slurry after emergency flood control during the rainy season; - Maneuvering in narrow streets and residential communities (vehicle width