As analysed in detail in the previous section, the BTL-FT process — as any XTL process — can yield a different range of products, ranging from chemicals and gasoline range hydrocarbons to middle distillate range alkanes, based on the FT synthesis reaction operating conditions, choice of catalyst and reactor type. The BTL-FT process has been, however, mainly studied so far with the aim to maximize the production of diesel range products due to two main reasons: the decisive shift of EU towards a diesel economy and the increasing EU diesel deficit in terms of refining capacity (European Biodiesel Board, 2008). International Energy Agency (IEA) figures presented in Fig. 19.13 clearly show the upward trend of the diesel demand in the EU compared to the downward trend of gasoline consumption. In addition, EU car registration figures show that the majority of new cars purchased are diesel cars (70% of new cars in France, Italy, Belgium are diesel cars) (ACEA, 2008). In this context, interest in the BTL-FT process lays in the production of renewable, high-quality middle distillate fuels via the LTFT synthesis reaction to diesel, naphtha and FT waxes and subsequent upgrading of the FT waxes to premium diesel. With such BTL-FT configuration, BTL naphtha is produced both as a straight-run and as a co-product of the FT wax upgrading. We will, therefore, focus on the properties and combustion characteristics of the two main BTL-FT final fuel products: diesel and naphtha.