Hohhot National VI Dongfeng 3308 mm wheelbase sewage treatment vehicle procurement case: An efficient solution for low-temperature environments. Against the backdrop of the full implementation of the National VI emission standard, a municipal sanitation department in Hohhot City, Inner Mongolia, launched a procurement project for sewage treatment vehicles in Q4 2025 to replace aging units and enhance winter sewage treatment efficiency. This project focused on National VI-compliant Dongfeng chassis models with a 3308 mm wheelbase, specifically addressing challenges including freeze-resistant cold-start capability, low-temperature hydraulic system stability, and winter maintenance. Chengli Special Purpose Vehicle Co., Ltd. (hereinafter 'Chengli') delivered these vehicles based on its proven technical solutions and localized service support. Policy Background: National VI Transition and Phasing-Out Timeline for Older Vehicles According to requirements set by China’s Ministry of Ecology and Environment, all heavy-duty diesel vehicles have been required to comply with the National VI emission standard since July 2021. By 2025, many regions—including Hohhot—have established clear phase-out schedules for vehicles meeting National III or lower emission standards. The municipal sanitation department previously operated several non-compliant sewage vehicles, whose hydraulic systems frequently failed under extreme winter conditions (–20°C to –30°C), significantly impairing operational efficiency. Therefore, this procurement mandated compliance with the National VIb standard, along with high-performance freeze resistance and low-temperature adaptability. Core Project Requirements and Chengli’s Solution The department’s public tender specified the following key requirements: chassis based on the Dongfeng 3308 mm wheelbase (approx. 3.3 m), rated payload capacity of ~3–5 tons, upper-body sewage tank (3–5 m³), and standard equipment including vacuum pump and liquid level control system. Chengli provided a customized solution based on its CLW5070GSSD6 model, which carries complete official certification and supports nationwide registration and annual inspection. Freeze-Resistant Cold-Start Performance: Chengli’s solution incorporates a low-temperature cold-start assistance system, including engine pre-heating devices and antifreeze coolant circulation, ensuring successful first-time start-up at –25°C. Low-Temperature Hydraulic Stability: The hydraulic system employs low-temperature-resistant seals and specialized hydraulic oil to minimize risks of oil solidification at sub-zero temperatures, ensuring smooth suction and discharge operations. Winter Maintenance Program: Chengli offers a dedicated winter maintenance package, including antifreeze coolant, low-temperature engine oil, and pipe heating tapes, backed by 24-hour direct-parts delivery service. Procurement Process and Award Information According to publicly available tender information, the project budget was capped at approximately RMB X million, covering five sewage treatment vehicles. As a direct manufacturer, Chengli offered cost savings of RMB 8,000–15,000 per unit compared to 4S dealership channels. Chengli ultimately won the bid at an average unit price of approximately RMB X million (per publicly disclosed tender data), with a delivery lead time of 15 days. The chassis is covered by Dongfeng’s nationwide warranty, while the upper-body assembly enjoys Chengli’s lifetime service commitment. Performance Comparison: Chengli Solution vs. Comparable Market Models The table below presents key performance comparisons between Chengli’s CLW5070GSSD6 and competing models at the same class, based on MIIT-certified parameters (e.g., CLW5070GSSD6) and industry procurement practices: Performance Indicator Chengli CLW5070GSSD6 Competing Model A Chassis Model Dongfeng 3308 mm wheelbase Dongfeng 3308 mm wheelbase Emission Standard National VIb National VIb Tank Capacity 4 m³ 4 m³ Cold-Star