In 2021, the German road transport sector emitted over 145 million tons of CO2-equivalents, with 92% of energy consumption coming from fossil fuels like petrol and diesel. To meet net climate neutrality by 2045, fossil fuel use must be phased out. This transition requires technological solutions such as zero-emission vehicles, but can also be supported by the use of synthetic fuels. Synthetic fuels provide a high energy density similar to fossil fuels, enabling large vehicle ranges and compatibility with existing infrastructure. In order to estimate the market potential of these fuels, an e-fuel scenario was being created using DLR’s vehicle technology scenario model VECTOR21 simulating yearly passenger and commercial vehicle purchase decisions. Based on forecasts for large-scale e-fuel production, costs are estimated to fall to 2.62 Euro/l by 2050. The possibility of registering e-fuel only vehicles would result in 10 % fewer battery electric vehicles in the fleet in 2040, resulting in a maximum demand for synthetic fuels in the e-fuel scenario of up to 133 TWh/year. As this is 2.8 times more than the projects announced worldwide for the production of synthetic fuels and also considering other sectors that are highly dependent on the use of synthetic energy sources, such as aviation or shipping, the use of electricity-based fuels on this scale in road transport is currently not to be expected. Without the potential approval of e-fuel only vehicles, the additional fuel demand of 48 TWh/year for these vehicles in the e-fuel scenario could be eliminated, which would cut the need for synthetic fuels to defossilize road transport in half in 2050.