Case Study and Renewal Procurement Plan Analysis: Xining Municipal Government’s Procurement of National VI Dongfeng 3308 mm Wheelbase Sewage Treatment Vehicles — In 2022, a municipal sanitation department in Xining procured three National VI Dongfeng 3308 mm wheelbase sewage treatment vehicles via public tender to address urban sewer network cleaning and emergency response needs. After delivery, the vehicles demonstrated stable performance under high-altitude low-temperature conditions; their freeze-resistant starting capability and low-temperature hydraulic system stability were highly commended by frontline operators. In 2024, the department initiated a new procurement round with clear intent to renew the contract and expand the order to five units. This article analyzes the procurement background, user feedback, and renewal plan based on real-world experience, providing reference for other procurement entities with similar requirements. I. Background and Vehicle Configuration of the Initial 2022 Procurement Xining is located on the Qinghai-Tibet Plateau, where the average winter temperature ranges from −10°C to −15°C, and extreme lows can reach −25°C. Conventional sewage treatment vehicles often suffer from difficult cold starts, hydraulic oil solidification, and pipeline freezing under such low temperatures—seriously compromising operational efficiency. In 2022, after comparing multiple vehicle models, the municipal sanitation department selected the National VI Dongfeng 3308 mm wheelbase sewage treatment vehicle manufactured by Chengli Special Purpose Vehicle Co., Ltd. According to publicly available tender information, the unit price of the first batch was approximately RMB 280,000, with a total budget of about RMB 947,000. The vehicle features an original Dongfeng chassis, a 3308 mm wheelbase, and a National VI-compliant engine, paired with a fully hydraulic drive system. Key configurations include: • Freeze-Resistant Starting System: Equipped with a chassis preheating device and low-temperature battery, enabling reliable engine start-up at −25°C without additional antifreeze additives. • Low-Temperature Hydraulic Stability: The hydraulic system employs low-temperature-resistant seals and synthetic hydraulic oil, extending its operational temperature range to −30°C–80°C, ensuring no oil solidification or flow restriction in sub-zero conditions. • Winter Maintenance Program: Includes a dedicated winter maintenance manual covering engine preheating procedures, recommended synthetic hydraulic oil replacement intervals, and pipeline thermal insulation measures. II. User Feedback: Outstanding Performance in Freeze Resistance and Hydraulic Stability After delivery, the department reported three key operational experiences: • Reliable Freeze-Resistant Starting: During the 2022 winter season, Xining experienced multiple episodes of severe cold weather below −20°C; all vehicles started successfully on the first attempt, with no incidents of battery discharge or ignition failure caused by low temperatures. • Stable Hydraulic System Performance: Frequent use of hydraulic pumps and pipelines under low-temperature conditions revealed no hydraulic oil solidification or seal leakage, maintaining operational efficiency comparable to that under normal ambient temperatures. • Low Maintenance Costs: Following the prescribed winter maintenance schedule, each vehicle required only one synthetic hydraulic oil change per quarter; routine maintenance intervals remained identical to those of standard vehicles, generating no additional maintenance expenses. A department head stated: “These vehicles have resolved our longstanding winter operation challenges—especially regarding freeze-resistant starting and hydraulic stability—giving us strong confidence in future procurements.” III. 2024 Renewal and Expanded Procurement Plan Based on the outstanding performance of the 2022 vehicles, the department decided in 2024 to renew the procurement co