Driving with cleaner engines: The evolution of diesel heavy-duty vehicles in China 2014–2024

Over the past decade, China’s heavy-duty vehicle (HDV) fleet has undergone a major transformation, with diesel trucks and buses becoming cleaner and more efficient thanks to stronger fuel consumption standards and advances in engine technology. Diesel vehicles still make up most of the market, but natural gas and electric models are gaining ground, together accounting for nearly a quarter of new HDV sales in 2024. The tightening of China’s fuel consumption standards, particularly from Stage 3 onward, has driven measurable reductions in fuel use and CO₂ emissions, with many manufacturers already meeting the upcoming Stage 4 limits ahead of schedule.

Figure. Evolution of diesel HDV specifications and type-approved CO2 emissions from 2014 to 2024

Key policy takeaways:

• Progressive standards drive real emissions reductions. China’s Stage 3 standards achieved measurable CO2 reductions across heavy-duty vehicles, enabling sustained progress in lowering emissions even as freight demand grows.
• Well-calibrated regulations balance performance and environment. Properly designed fuel consumption standards successfully reduced emissions despite increases in engine power and payload capacity driven by operational demands.
• Early compliance signals regulatory readiness. Manufacturers met Stage 4 requirements before enforcement, indicating that clear regulatory timelines enable industry preparation and technological advancement.
• Different vehicle segments require tailored policies. Trucks and buses responded differently to regulations, with electrification reshaping buses while freight vehicles improved efficiency, underscoring segment-specific policy needs.