The customs of the destination country has the right to disregard the commercial invoice and reassess the value based on its internal database (such as the customs valuation red book). Any additional duties incurred are a result of the importing country's policy and are fully borne by the buyer (importer).

From a technical perspective, China's "National VI B (China VI-b)" is one of the strictest emission standards globally, with limits on carbon monoxide, nitrogen oxides, and particulate matter that are even stricter than some of Europe's Euro VI standards. However, the two are not legally recognized by each other, depending on your country's import regulations.

No, this is a serious customs violation. Complete vehicles (HS Code 8703) and auto parts (HS Code 8708, etc.) are subject to completely different import tax rates. Combining them on one invoice could lead to the invoice being returned by customs and may expose you to tax fraud accusations at the destination port.