Government procurement case of Dongfeng sewage treatment vehicles in Cangzhou: Winning proposal and cost analysis amid the transition to China VI emission standards. Against the backdrop of full implementation of China VI emission standards, municipal sanitation departments nationwide are accelerating the phasing out of aging vehicles and shifting toward environmentally compliant equipment. A district urban management bureau in Cangzhou, Hebei Province recently completed a procurement project for a batch of Dongfeng sewage treatment vehicles, with a budget capped at approximately X ten-thousand RMB, ultimately selecting Chengli Special Purpose Vehicle Co., Ltd.'s China VI-compliant solution. This article uses this case as a starting point, integrating policy context, timelines for retiring older vehicles, subsidy stacking strategies, and Chengli’s actual delivery performance, offering procurement entities a practical decision-making reference. I. Policy Context of the China VI Transition and Timeline for Retiring Older Vehicles According to the implementation schedule for China VI heavy-duty diesel vehicle emission standards issued by China’s Ministry of Ecology and Environment: effective July 1, 2021, all heavy-duty diesel vehicles manufactured, imported, sold, or registered must comply with China VIa standards; and as of July 1, 2023, China VIb standards became fully mandatory. This means that municipal sanitation vehicles registered around 2019 or earlier—meeting China V or lower emission standards—are already facing restrictions on operation or mandatory retirement in certain regions. In Cangzhou, for example, local environmental authorities have explicitly mandated that, by the end of 2025, China III and lower-emission-standard sanitation vehicles be largely phased out from urban built-up areas, while China IV vehicles will progressively enter the retirement scope. For sewage treatment vehicles—which operate frequently and accumulate high mileage—the retirement timeline is even more urgent: many units deployed between 2015 and 2018 have become operationally unsustainable due to noncompliance with current emissions requirements and rising maintenance costs. Against this backdrop, a district urban management bureau in Cangzhou launched a fleet renewal procurement initiative in the second half of 2025, prioritizing sewage treatment vehicles as critical equipment for maintaining urban sewer networks. Procurement requirements were clearly stipulated: vehicles must meet China VIb emission standards; chassis must demonstrate high reliability; superstructures must conform to local sewage treatment operational specifications; and the overall budget must remain within a reasonable range. II. Chengli’s China VI Solution: Customized Integration of Dongfeng Chassis and Superstructure After multiple rounds of technical evaluation and open tendering, Chengli Special Purpose Vehicle Co., Ltd. was selected based on its mature China VI product portfolio and extensive delivery experience, providing a Dongfeng-based sewage treatment vehicle solution. The core model offered was CLW5070GSSD6 (official announcement model), built upon the Dongfeng Dorica series chassis and powered by a Yuchai China VI-compliant diesel engine with a rated power output of approximately 85 kW, fully meeting China VIb emission requirements. The superstructure features a sewage pump, filtration system, water storage tank, and automated control unit. Per official announcement parameters, the tank’s effective capacity is approximately 5 cubic meters—adequate for routine urban tasks such as manhole cleaning and pipeline unclogging. Chengli’s solution for this procurement offers the following key advantages: • OEM Chassis Warranty: Dongfeng chassis covered under nationwide warranty service, with authorized service centers widely distributed across Cangzhou and surrounding regions—ensuring high vehicle availability. • Lifetime Superstructure Support: Chengli guarantees