Government procurement case and bid-winning solution analysis of the National VI Dongfeng 3308 mm wheelbase sewage treatment vehicle in Zunyi — In the municipal sanitation sector, selection of special-purpose vehicles directly impacts operational efficiency and long-term operating costs. This article analyzes a recent procurement case by a district urban management bureau in Zunyi—specifically, its acquisition of National VI Dongfeng 3308 mm wheelbase sewage treatment vehicles—from perspectives including residual value retention, adaptability to hot-humid environments, and key configuration features, providing reference for future procurements. I. Case Background: Procurement Requirements under Zunyi’s Hot-Humid Climate Zunyi is located in northern Guizhou Province, characterized by a hot, humid, and rainy climate with a long rainy season and high ambient humidity. A local municipal sanitation department required procurement of a batch of sewage treatment vehicles for urban pipeline cleaning and sewage transportation. Tender requirements explicitly specified: National VI emission standard, anti-corrosion coating, sealing components resistant to hot-humid conditions, and chassis load capacity ≥ 3.5 tons. Ultimately, Chengli Special Purpose Vehicle Co., Ltd. (hereinafter referred to as “Chengli”) delivered approximately six sewage treatment vehicles based on the Dongfeng 3308 mm wheelbase chassis, at a unit price of around RMB 145,000 (based on publicly available tender information). These vehicles have been operating in Zunyi’s urban area for over eight months, with stable customer feedback. II. The Used-Vehicle Market After Three Years: Residual Value Comparison In the special-purpose vehicle sector, residual value is a critical indicator reflecting overall vehicle quality and brand after-sales service capability. Based on industry circulation data and Chengli’s used-vehicle transaction records from the past three years, the residual value performance of Chengli’s National VI Dongfeng 3308 mm wheelbase sewage treatment vehicles after three years is as follows: Chengli Vehicle Residual Value Comparison (benchmark: 3-year-old vehicles with 80,000–100,000 km mileage) | Model | Initial Purchase Price (based on publicly available tender information) | Estimated Used Market Price after 3 Years | Residual Value | Key Advantages | |-------|---------------------------------------------------------------------|------------------------------------------|----------------|----------------| | Chengli National VI Dongfeng 3308 Sewage Treatment Vehicle | ~RMB 145,000 | ~RMB 102,000 | ~70% | Anti-corrosion coating, durable sealing components, nationwide chassis warranty | | Competitor A (a certain brand), same class | ~RMB 150,000 | ~RMB 90,000 | ~60% | No specialized anti-corrosion treatment; rapid aging of sealing components | | Competitor B (a certain brand), same class | ~RMB 140,000 | ~RMB 78,000 | ~56% | Non-mainstream chassis; difficult parts sourcing | As shown in the table, Chengli’s model demonstrates higher residual value in hot-humid environments due to superior anti-corrosion coating and sealing component durability. Zunyi customers reported no visible rust on tanks or pipelines, nor any leakage signs from sealing components, even after frequent operations during the rainy season. III. Key Configurations Affecting Residual Value: Anti-Corrosion Coating and Sealing Component Durability In hot-humid, rainy regions like Zunyi, two core factors primarily influence the residual value of sewage treatment vehicles: 1. Anti-Corrosion Coating Chengli applies a dual-layer primer-and-topcoat anti-corrosion process to sewage treatment vehicle tanks and chassis frames, supplemented by corrosion-resistant epoxy resin spray at critical weld seams. This configuration was validated in the Zunyi case: after eight consecutive months of operation in high-humidity conditions, the vehicle’s paint film remained intact without blistering or p