The transport industry is moving towards decarbonization, with hydrogen emerging as a key player in this transition. While fuel cells are often in the spotlight, there is a growing interest in using hydrogen in internal combustion engines to power trucks. Westport Fuel Systems and Volvo Group have established a joint venture to enhance the adoption of hydrogen high-pressure direct injection (HPDI) fuel systems for internal combustion engines. Testing has shown that directly injecting hydrogen into internal combustion engines can provide advantages over fuel cells, achieving similar energy efficiency in heavy-duty applications. Volvo Group, a significant player in this sector, has invested in various technologies as part of its decarbonization strategy. They emphasize a three-pronged approach incorporating battery-electric vehicles, fuel-cell-electric vehicles, and internal combustion engines that use zero-carbon fuels such as hydrogen. The newly formed HPDI technology joint venture aligns with Volvo's strategy of utilizing zero-carbon internal combustion engines. In a comparison of thermal efficiency and energy-to-work conversion between fuel cells and HPDI hydrogen engines, both technologies showcase promising results. While fuel cell trucks achieve around 50-55% thermal efficiency in heavy-duty applications, HPDI technology allows achieving similar or even better thermal efficiency than traditional diesel engines. Notably, the comparison indicates that fuel cells excel at low loads, whereas engines perform better under high load factors typical of heavy-duty truck applications. Lars Stenqvist, CTO of Volvo Group, highlights the importance of considering regional preferences and energy availability when selecting between fuel cells and internal combustion engines fueled by hydrogen. The choice of technology for transport applications will not solely rely on engineering decisions but also on factors like energy pricing across different regions. This flexible approach may lead to the coexistence of battery-electric vehicles, fuel-cell-electric vehicles, and hydrogen-fueled internal combustion engines based on regional needs and energy landscapes.