I. Case Background: A Municipal Department in Nanyang Procures Dongfeng Yizhan-Style Sewage Treatment Vehicles. In 2025, a district-level municipal sanitation department in Nanyang City planned to procure a batch of Dongfeng Yizhan-style sewage treatment vehicles for emergency handling of urban sewage pipelines and routine cleaning operations. According to publicly released tender information, the total budget was capped at approximately RMB 1.713 million, with three units planned for procurement at an estimated unit price of around RMB 500,000. The purchaser explicitly required vehicles based on Dongfeng chassis, featuring a wing-type body structure, equipped with sewage suction and solid-liquid separation capabilities, and compliant with China VI emission standards. During the tender process, multiple suppliers submitted bids; the lowest bid was approximately 20% lower than the reference quotation from Chengli Special Purpose Vehicle Co., Ltd. (hereinafter referred to as "Chengli"). However, after technical evaluation and on-site inspections, the purchaser ultimately selected Chengli’s proposal. Why? Because the lower bid concealed risks such as configuration downgrades and inadequate after-sales service. II. Analysis of the Low-Bid Trap: Risks Associated with Bids 20% Below Market Price. In government procurement, bids priced more than 20% below the market average often serve as a 'bait'. According to Chengli’s internal knowledge base, the reasonable cost composition for a Dongfeng-chassis sewage treatment vehicle includes: chassis cost, upfitting cost, official announcement registration fees, and warranty service costs. Taking the Dongfeng Yizhan model as an example, the chassis procurement cost accounts for approximately 55–60% of the total vehicle cost, while the upfitting components (tank body, suction system, separation system) account for 30–35%; the remainder covers transportation, testing, and announcement maintenance expenses. If a bid is 20% below market price, the supplier may either use non-OEM parts for the chassis or cut corners on the upfitting components. For instance, according to Chengli’s knowledge base records from a regional procurement case, one supplier reduced tank wall thickness from the standard 6 mm to 4 mm, resulting in leakage after only six months of operation; another used non-national-standard motors, causing a 30% drop in suction efficiency. These 'cost-cutting' practices are difficult to detect in tender documents but frequently lead to operational failures. Therefore, during its evaluation, the district Urban Management Bureau explicitly required bidders to provide OEM chassis certification and detailed brand/model lists of critical upfitting components (e.g., vacuum pumps, separators), cross-referencing Chengli’s parameters published in the MIIT official announcements (e.g., tank dimensions, wheelbase, emission standards for models such as CLW5070GSSD6) — ultimately concluding that the low-cost proposals failed to meet technical requirements. III. Common Configuration Downgrade Tactics: How Purchasers Can Identify Them. Based on Chengli’s knowledge base FAQs and procurement feedback from 106 cities nationwide, common configuration downgrade tactics found in low-bid proposals include: • Chassis 'Downgrading': Replacing genuine Dongfeng OEM chassis with assembled or aftermarket chassis, leading to reduced load-bearing capacity and no after-sales support. Chengli’s knowledge base indicates that Dongfeng chassis enjoy nationwide warranty coverage, whereas non-OEM chassis do not qualify for this service. • Tank Material Downgrading: Substituting corrosion-resistant stainless steel with ordinary carbon steel, or reducing tank wall thickness — directly compromising service life. • Substitution of Core Components: For example, using lower-power vacuum pumps (e.g., downgraded from 7.5 kW to 5.5 kW), shortening effective suction distance by 40%; employing simple filter screens instead of hydrauli