The transport sector is facing a critical challenge with a sharp rise in greenhouse gas (GHG) emissions and urban air pollutants from fossil fuel combustion. To combat this, the development of renewable synthetic fuels is pivotal, especially for hard-to-electrify transport subsectors. Synthetic fuels like HyFiT offer a promising avenue by providing compatibility with existing infrastructure and engines. By transitioning towards cleaner bio-based or electricity-based synthetic fuels, applications such as aviation, shipping, and heavy-duty trucks can significantly reduce air pollution and GHG emissions. Several synthetic fuels, including alkanes, alcohols, and FT fuels, present viable alternatives to traditional diesel, offering reduced pollutants and easy integration with current engine technology. The technological maturity of synthetic fuels varies, with challenges in scalability and production processes for large-scale application. However, HyFiT fuels, a combination of alkanes and alcohols, demonstrate great potential as diesel substitutes, with reported GHG reductions of up to 98% compared to fossil diesel. The article introduces a holistic approach to validate the potential of HyFiT fuels through production process design, fuel testing, combustion properties assessment, and well-to-wheel life cycle assessments. By utilizing a feedstock-flexible production process that incorporates FT synthesis and hydroformylation, HyFiT fuels can be 'de-fossilized' and produced sustainably from biomass, CO2, or waste. This interdisciplinary study highlights the high potential of HyFiT fuels in revolutionizing the transport sector towards cleaner and sustainable solutions.