CN code 8701 21 covers road tractors for semi-trailers equipped with compression-ignition internal combustion engines (diesel). These are heavy goods vehicles of category N3, forming the backbone of European road freight transport. Modern tractor units feature engines with displacements from 10 to 16 litres and power outputs from 300 to 580 HP, meeting Euro VI emission standards under Regulation (EC) No 595/2009. From 2026, new vehicles must additionally take into account the upcoming Euro 7 requirements defined in Regulation (EU) 2024/1257. These tractors are equipped with advanced safety systems required by Regulation (EU) 2019/2144, including autonomous emergency braking, lane departure warning, blind spot detection, and intelligent speed assistance. Type-approval is carried out in accordance with Regulation (EU) 2018/858 and requires presentation of a Certificate of Conformity (CoC) issued by the manufacturer.

Importing diesel tractor units from outside the European Union requires completion of full customs procedures, including submission of a customs declaration, presentation of commercial and transport documents, and payment of customs duties and taxes. Duty rates for road tractors for semi-trailers should be verified in the TARIC or ISZTAR4 databases, as they may differ depending on the country of origin. Tractor units as N3 category motor vehicles are not subject to excise duty in Poland, which applies only to passenger cars. VAT is charged on the customs value plus duty. Vehicles imported from outside the EU must obtain type-approval or individual vehicle approval issued by the Transport Technical Supervision authority. A technical inspection by an authorised vehicle testing station and registration at the appropriate transport department are also required. For intra-EU acquisitions of tractors from another EU Member State, a simplified procedure applies with VAT settled through the tax return.

The European diesel tractor unit market (CN 8701 21) is dominated by manufacturers such as Mercedes-Benz, MAN, Scania, Volvo, DAF, and Iveco. In 2026, the sector faces increasing regulatory pressure related to CO2 emission reductions from heavy-duty vehicles under Regulation (EU) 2019/1242 as amended by Regulation (EU) 2024/1610, which sets CO2 reduction targets of 45% by 2030 and 90% by 2040 compared to the baseline level. This drives the development of alternative powertrain technologies, though diesel tractors continue to dominate long-haul transport due to the energy density of diesel fuel and well-developed refuelling infrastructure. For tariff classification purposes, it is important to distinguish between road tractors (heading 8701) and chassis with cab (heading 8704) – the decisive factor is the vehicle's intended use for towing semi-trailers rather than carrying loads on its own platform.