The ban on TEL (Tetra-Ethyl Lead) in the early of 1970s and also the installation of the two-way and then three-way catalytic converters in automobile exhaust since 1975, which were intolerant of lead, led the refinery industry to the use of high-octane oxygenated components, called “oxygenates” (US CAA Amendments 1977, 1990; EU Fuel Quality Directive 98/70/EC; Directive 2009/30/EC). Hitherto, ether oxygenates (MTBE, ETBE, TAME) are added to certain gasoline (petrol) formulations to improve combustion efficiency and to increase the octane rating, known as gasoline ether oxygenates (GEOs) or fuel-ethers. Greece, as well as Germany, Italy, Finland and France, produces and uses methyl tert-amyl ether (TAME) as GEO. However, despite the fact that TEL was replaced by GEOs, due to the environmental consequences and the severe human health effects of the former; it is worthy of remark that the GEOs took the place of TEL as suitable octane boosters in the refinery blended gasoline pool and not as environmentally benign compounds (Bonventre et al. 2012). An environmentally friendly two-step in situ synthesis of an upgraded fuel that could replace the harmful TAME from the refinery blended gasoline pool is being proposed. Moreover, it is noteworthy that the ultimate product (fuel) contains more oxygen providing better combustion properties and bigger octane numbers. The standard properties of the ultimate upgraded fuel are fully determined and the whole industrial process was modelled and simulated facilitating the implementation of the proposal at the industrial field.